Custom Shtml Errors

[digitaldrv]

I am running IIS 5.0. I want people to be able to browse a web site of mine and when they type in e.g.

http://www.1search4u.com/whatever.shtml

I want them to see my custom error page using shtml.

I've figured out how to do it when a user types in a htm, html or even a bogus extension it will redirect them to my home page, but I need it to work with shmtl.

Thanks
Daniel