During the configuration process in preparation to build a new release of perl on your system, there are a number of questions and settings that refer to the location of libraries. Essentially, these paths are "Compiled In"; however, you can always change the default during the build.

A nifty build trick is to add library paths to be added to the front of the @INC path, thus overriding the built-ins with your own modules, should you choose to do so.

The relevant portion of code is

sh Configure -Accflags='-DAPPLLIB_EXP=\"/other/lib/dir\"'
[download]

as per the CPAN Install - Build and Installation guide for perl5 page.

-v