Thanks, the symlink approach seems to fit what I'm after. There are subclasses in my module (Foo::Bar::Baz) so I guess I'll try linking the directory rather than just one file.
What I'm trying to do seems like it should be easy: make a module skeleton with h2xs, work on it in place, and finally make a release from it. The "work on it in place" is turning out to be surprisingly difficult. So far I've just installed it into a local directory (so that I don't have to edit it as root) and I'll have to copy it back into my release directory structure when I have a version that's ready to go. I can live with that, but I expected to be able to work on it directly in place after creating it with h2xs.
I'm using the module in the context of mod_perl, so being able to run it from scripts outside of the module's directory is necessary.