in reply to CPAN and Site Modules

You might like to look at using the native packaging system for your OS.

For example, on Debian GNU/Linux I do exactly the sorts of things you're describing using .deb files in apt repositories. Many of the common CPAN modules are already packaged as .debs and you can use the dh-make-perl utility to create a .deb from a CPAN-style tarball. The .deb format handles dependencies including system libraries that a Perl module might require.