How do I add a custom item to the top of a dropdown using the asp.net mvc Html.DropDownList helper?

I have a dropdown list on my asp.net mvc site:

<%= Html.DropDownList("CustCodes") %>

My controller:

 ICallService sc = new CallService();
 IList<CustCode> custCodes = sc.GetCustCodes();
 ViewData["CustCodes"] = new SelectList(custCodes, "ID", "Name");

What I want is once the dropdown is displayed to either have a blank entry at the top or an option that says "Select a Customer". Do I need to use jquery to do this or is there something built into the DropDowList helper that I'm missing?

Thanks.

From stackoverflow

• Use an override that contains an option label.

   <%= Html.DropDownList("CustCodes",
                         ViewData["CustCodes"] as SelectList,
                         "Select a Customer",
                         null ) %>