Show up a modal dialog on a view when a Unathorized event is thrown

Hi, 

I am trying to show a modal popup to inform the user that the link/action/resource he selected is no authorized for his role. I have decorated the function with a custom annotation 

[AutorizacionUsuarios (Roles = "Informatico") ]

And Override the HandleUnauthorizedRequest

protected override void HandleUnauthorizedRequest(System.Web.Mvc.AuthorizationContext filterContext)
    {
        if (filterContext.HttpContext.Request.IsAuthenticated)
        {
            filterContext.Result = new System.Web.Mvc.HttpStatusCodeResult((int)System.Net.HttpStatusCode.Forbidden);
        }
        else
        {
            base.HandleUnauthorizedRequest(filterContext);
        }

But it generates a new page/view with the error info, I would need to show a modal popup dialog on the view/controller that generate the call to the unauthorized functions.

As an example:

If call the funtion Home/GoToClientsList  from a button on Home/Index that redirecto to Clients/Index and this function is not authorized for the usere's roles then I would like to show a modal popup on Home/Index informing the user about.