I like to maintain separate environments when the stability and predictability of “one particular environment” is important for some reason.   I always do this with regard to CPAN modules, e.g. keeping a separate collection for every website on a shared server.   If the operating system in question uses Perl for its management toolchain (as many Linux distros do), I go ahead and install a local Perl executable as well, so that I can safely do “my” stuff while they do “theirs.”   (This local install may or may not be in /usr/local/bin, because I do not want to interfere with the vendor’s public code, but it will always be in the necessary $PATHs.)

OS/X is a reasonably well-behaved Unix system if you are willing to step outside of Apple’s easy and well-padded room.   It plays by different rules in some respects but it does “play well with others.”   Especially if you are comfortable doing things without a ready-made installer, the procedure is unremarkable.