Topic: OpenLayers – Custom Feature Style
Descriptions: To enable custom style to a particular feature by using renderIntent & adding new styleMap.

1. Get Feature; var o = target_layer.features[3];
2. Set Style Name; var styleName = o.id + '_style';
3. Set render intent; o.renderIntent = styleName;
4. Set the custom style; var style = new OpenLayers.Style({externalGraphic:'icons/marker_1.png'});
5. Add new style to styleMap; o.layer.styleMap.styles[styleName] = style;
6. Assign back to the layer’s feature; target_layer.features[3] = o;
7. Call redraw method in o.layer; o.layer.redraw();