By default, perl will still use the @INC that is compiled into it. And it will still use the environment variable PERL5LIB, if it's set. (If not, it'll try PERLLIB as well.) So, if the dependant modules are already in the standard location, Makefile.PL should be able to find them and be satisfied. If you've installed to a second local directory, don't do that, but you can set PERL5LIB for that. If someone came up with the bright idea of a shared local directory (i.e., one person installs for a group), but you need more on top of that, PERL5LIB can help there, too.

Even if it's already in ~/lib, you may need to set PERL5LIB to include that path - I can't recall offhand.