一部のデフォルト列を削除し、顧客グリッドに列を追加する必要がありました。列を構成可能にすることにしました。最初にsystem.xmlに 2つの複数選択ボックスを追加しました。
<config>
    <sections>
        <extendedcustomer translate="label" module="extendedcustomer">
            <label>Extended Customer</label>
            <tab>customer</tab>
            <sort_order>100</sort_order>
            <show_in_default>1</show_in_default>
            <show_in_website>1</show_in_website>
            <show_in_store>1</show_in_store>
            <groups>
                <manage_grid translate="label">
                    <label>Manage Customer Grid in Backend</label>
                    <frontend_type>text</frontend_type>
                    <sort_order>10</sort_order>
                    <show_in_default>1</show_in_default>
                    <show_in_website>1</show_in_website>
                    <show_in_store>1</show_in_store>
                    <fields>
                        <remove translate="label">
                            <label>Remove Columns</label>
                            <frontend_type>multiselect</frontend_type>
                            <source_model>extendedcustomer/source_gridColumn</source_model>
                            <sort_order>10</sort_order>
                            <show_in_default>1</show_in_default>
                            <show_in_website>1</show_in_website>
                            <show_in_store>1</show_in_store>
                        </remove>
                        <add translate="label">
                            <label>Add Columns</label>
                            <frontend_type>multiselect</frontend_type>
                            <source_model>extendedcustomer/source_attributeCode</source_model>
                            <sort_order>20</sort_order>
                            <show_in_default>1</show_in_default>
                            <show_in_website>1</show_in_website>
                            <show_in_store>1</show_in_store>
                        </add>                       
                    </fields>
                </manage_grid>
            </groups>
        </extendedcustomer>
    </sections>
</config>
ソースモデルは単純です。
class SomeCo_ExtendedCustomer_Model_Source_GridColumn
{
    public function toOptionArray()
    {     
        return [
            ['value' => 'name', 'label' => 'Name'],
            ['value' => 'email', 'label' => 'Email'],
            ['value' => 'group', 'label' => 'Group'],
            ['value' => 'billing_telephone', 'label' => 'Telephone'],
            ['value' => 'billing_postcode', 'label' => 'ZIP'],
            ['value' => 'billing_country_id', 'label' => 'Country'],
            ['value' => 'billing_region', 'label' => 'State/Province'],
            ['value' => 'customer_since', 'label' => 'Customer Since'],
            ['value' => 'website_id', 'label' => 'Website'],
            ['value' => 'action', 'label' => 'Action']
        ];
    }
}
2番目のソースモデル
class SomeCo_ExtendedCustomer_Model_Source_AttributeCode
{
    public function toOptionArray()
    {     
        $collection = Mage::getResourceModel('customer/attribute_collection')
            ->addFieldToSelect(['attribute_code', 'frontend_label'])
            ->addFieldToFilter('frontend_label', ['notnull'=>'notnull'])
            ->addFieldToFilter('is_user_defined', 1);
        $options = [];
        foreach ($collection as $item) {
            $options[] = [
                'value'     => $item->getData('attribute_code'),
                'label'     => $item->getData('frontend_label')
            ];
        }
        return $options;
    }
}
次に、グリッドクラスをオーバーライドします。
class SomeCo_ExtendedCustomer_Block_Adminhtml_Customer_Grid extends Mage_Adminhtml_Block_Customer_Grid
{
    public function __construct()
    {
        parent::__construct();
        if ($remove = Mage::getStoreConfig('extendedcustomer/manage_grid/remove')) {
            $remove = explode(',', $remove);
        } else {
            $remove = false;
        }
        $this->setRemoveList($remove);
        if ($add = Mage::getStoreConfig('extendedcustomer/manage_grid/add')) {
            $add = explode(',', $add);
        } else {
            $add = false;
        }
        $this->setAddList($add);
    }
    protected function _prepareCollection()
    {
        if ($remove = $this->getRemoveList()) {
            $collection = Mage::getResourceModel('customer/customer_collection');
            if (!in_array('name', $remove)) {
                $collection->addNameToSelect();
            }
            foreach (['postcode', 'city', 'telephone', 'region', 'country_id'] as $suffix) {
                if (!in_array('billing_'.$suffix, $remove)) {
                    $collection->joinAttribute('billing_'.$suffix, 'customer_address/'.$suffix, 'default_billing', null, 'left');
                }
            }
        } else {
            $collection = Mage::getResourceModel('customer/customer_collection')
                ->addNameToSelect()
                //->addAttributeToSelect('email') // static attributes are added by default
                //->addAttributeToSelect('created_at')
                //->addAttributeToSelect('group_id')
                ->joinAttribute('billing_postcode', 'customer_address/postcode', 'default_billing', null, 'left')
                ->joinAttribute('billing_city', 'customer_address/city', 'default_billing', null, 'left')
                ->joinAttribute('billing_telephone', 'customer_address/telephone', 'default_billing', null, 'left')
                ->joinAttribute('billing_region', 'customer_address/region', 'default_billing', null, 'left')
                ->joinAttribute('billing_country_id', 'customer_address/country_id', 'default_billing', null, 'left');
        }
        if ($add = $this->getAddList()) {
            $collection->addAttributeToSelect($add);
        }
        $this->setCollection($collection);
        return Mage_Adminhtml_Block_Widget_Grid::_prepareCollection(); // call grandParent
    }
    protected function _prepareColumns()
    {
        $this->addColumn('entity_id', array(
            'header'    => Mage::helper('customer')->__('ID'),
            'width'     => '50px',
            'index'     => 'entity_id',
            'type'  => 'number',
        ));
        $remove = $this->getRemoveList();
        if (!$remove || !in_array('name', $remove)) {           
            $this->addColumn('name', array(
                'header'    => Mage::helper('customer')->__('Name'),
                'index'     => 'name'
            ));
        }
        if ($add = $this->getAddList()) {
            $collection = Mage::getResourceModel('customer/attribute_collection')
                ->addFieldToSelect(['attribute_code', 'frontend_label', 'source_model'])
                ->addFieldToFilter('attribute_code', ['in' => $add]);
            foreach ($collection as $item) {
                if ($source = $item->getSourceModel()) {
                    $this->addColumn($item->getAttributeCode(), array(
                        'header'    =>  $item->getFrontendLabel(),
                        'width'     =>  '100',
                        'index'     =>  $item->getAttributeCode(),
                        'type'      =>  'options',
                        'options'   =>  Mage::getSingleton($source)->toOptionHash(false)
                    ));
                } else {
                    $this->addColumn($item->getAttributeCode(), array(
                        'header'    => $item->getFrontendLabel(),
                        'width'     => '150',
                        'index'     => $item->getAttributeCode()
                    ));
                }
            }
        }
        if (!$remove || !in_array('email', $remove)) {            
            $this->addColumn('email', array(
                'header'    => Mage::helper('customer')->__('Email'),
                'width'     => '150',
                'index'     => 'email'
            ));
        }
        if (!$remove || !in_array('group', $remove)) {
            $groups = Mage::getResourceModel('customer/group_collection')
                ->addFieldToFilter('customer_group_id', array('gt'=> 0))
                ->load()
                ->toOptionHash();
            $this->addColumn('group', array(
                'header'    =>  Mage::helper('customer')->__('Group'),
                'width'     =>  '100',
                'index'     =>  'group_id',
                'type'      =>  'options',
                'options'   =>  $groups,
            ));
        }
        if (!$remove || !in_array('billing_telephone', $remove)) {
            $this->addColumn('Telephone', array(
                'header'    => Mage::helper('customer')->__('Telephone'),
                'width'     => '100',
                'index'     => 'billing_telephone'
            ));
        }
        if (!$remove || !in_array('billing_postcode', $remove)) {
            $this->addColumn('billing_postcode', array(
                'header'    => Mage::helper('customer')->__('ZIP'),
                'width'     => '90',
                'index'     => 'billing_postcode',
            ));
        }
        if (!$remove || !in_array('billing_country_id', $remove)) {
            $this->addColumn('billing_country_id', array(
                'header'    => Mage::helper('customer')->__('Country'),
                'width'     => '100',
                'type'      => 'country',
                'index'     => 'billing_country_id',
            ));
        }
        if (!$remove || !in_array('billing_region', $remove)) {
            $this->addColumn('billing_region', array(
                'header'    => Mage::helper('customer')->__('State/Province'),
                'width'     => '100',
                'index'     => 'billing_region',
            ));
        }
        if (!$remove || !in_array('customer_since', $remove)) {
            $this->addColumn('customer_since', array(
                'header'    => Mage::helper('customer')->__('Customer Since'),
                'type'      => 'datetime',
                'align'     => 'center',
                'index'     => 'created_at',
                'gmtoffset' => true
            ));
        }
        if (!$remove || !in_array('website_id', $remove)) {
            if (!Mage::app()->isSingleStoreMode()) {
                $this->addColumn('website_id', array(
                    'header'    => Mage::helper('customer')->__('Website'),
                    'align'     => 'center',
                    'width'     => '80px',
                    'type'      => 'options',
                    'options'   => Mage::getSingleton('adminhtml/system_store')->getWebsiteOptionHash(true),
                    'index'     => 'website_id',
                ));
            }
        }
        if (!$remove || !in_array('action', $remove)) {
            $this->addColumn('action',
                array(
                    'header'    =>  Mage::helper('customer')->__('Action'),
                    'width'     => '100',
                    'type'      => 'action',
                    'getter'    => 'getId',
                    'actions'   => array(
                        array(
                            'caption'   => Mage::helper('customer')->__('Edit'),
                            'url'       => array('base'=> '*/*/edit'),
                            'field'     => 'id'
                        )
                    ),
                    'filter'    => false,
                    'sortable'  => false,
                    'index'     => 'stores',
                    'is_system' => true,
            ));
        }
        $this->addExportType('*/*/exportCsv', Mage::helper('customer')->__('CSV'));
        $this->addExportType('*/*/exportXml', Mage::helper('customer')->__('Excel XML'));
        return Mage_Adminhtml_Block_Widget_Grid::_prepareColumns();
    }
}
               
              
$block->getCollection()