Do you plan to release your code on CPAN? (Just curious)

If we want this to be as general as possible, then I could add a specialised hook for unknown schemes that would return false if the protocol is really not supported and another URL to try otherwise.

In your case, the callback would simply return "http://homepage".

What do you think of this? It should work for you and possibly for future users having even more esoteric needs than you. :-)