Custom Error Redirects

I've reviewed several posts on here and on other forums and I cannot get the my sitefinity site to redirect the url http://www.mysite.com/pirate (made up of course).  The pirate part of the url isn't getting past IIS6's error page.  I've have my aspnet_isapi.dll set as a wildcard mapping so it should be accepting all of these requests so Sitefinity can handle.  I am wondering if anyone got this working?

I also have the custom error section turned on in my web.config.  It handles all other requests but the above instance.

I know I can setup my own custom .ashx file which I can point IIS to hit directly in the case of a 404 so I can handle it where I want but I didn't want to have an extra request if I could handle it.

Any ideas?