回答:
レイヤーを定義するときに、styleMapsも指定できます。
_layer = new OpenLayers.Layer.Vector("My Layer Name", {
    styleMap: new OpenLayers.StyleMap({
        "default": new OpenLayers.Style({
            strokeColor: "#ff0000",
            strokeOpacity: .7,
            strokeWidth: 1,
            fillColor: "#ff0000",
            fillOpacity: 0,
            cursor: "pointer"
        }),
        "temporary": new OpenLayers.Style({
            strokeColor: "#ffff33",
            strokeOpacity: .9,
            strokeWidth: 2,
            fillColor: "#ffff33",
            fillOpacity: .3,
            cursor: "pointer"
        }),
        "select": new OpenLayers.Style({
            strokeColor: "#0033ff",
            strokeOpacity: .7,
            strokeWidth: 2,
            fillColor: "#0033ff",
            fillOpacity: 0,
            graphicZIndex: 2,
            cursor: "pointer"
        })
    })
});次にあなたを指定してくださいrenderintent:
_highlightControl = new OpenLayers.Control.SelectFeature(layer, {
    hover: true,
    highlightOnly: true,
    renderIntent: "temporary"
});