"Fixing your cpan would be the answer as above, but you can use the following to add an extra directory (or more) for your script to access modules not in your usual path: http://perldoc.perl.org/lib.htm"

cpan isn't broken, and doesn't require fixing. Note that your suggestion introduces the binary incompatibility problem.

As a side note What shortcuts can I use for linking to other information?, [doc://lib] -> lib.