I had to do this today, and found two blog entries that made it really easy. I figure I’ll have to do this again at some point, so I’m putting them here for easy reference, and to give this guy another link, which he deserves.
http://blog.codeville.net/2008/07/04/options-for-deploying-aspnet-mvc-to-iis-6/
http://blog.codeville.net/2008/07/07/overriding-iis6-wildcard-maps-on-individual-directories/