URL Routing and QueryStrings in ASP.NET Web Forms application

I am trying to implement URL Routing for a non MVC application. Here's my original URL:

http://mydomain.com/ProcessStuff.aspx?id=1029019

to

http://mydomain.com/Process-This-Stuff/1029019

I have difficulty when the page has query strings in the URL.

This is the route handler I have so far:

public class CustomRouteHandler : IRouteHandler
{
    public IHttpHandler GetHttpHandler(RequestContext requestContext)
    {
        return BuildManager.CreateInstanceFromVirtualPath("ProcessStuff.aspx", typeof(Page)) as Page;
    }
}