PERL5LIB is an environment variable, not a module, and should be set to 'point to' the location of the alternate library location(s) (if any) such that the command perl -V should contain a list of all the standard library locations for your installation together with any alternate locations.

Since neither /Library/Perl/5.8.6 or /System/Library/Perl/5.8.6 are standard locations, I would infer that PERL5LIB isn't being used, as it ought, to do its job - what you need, I'm guessing, is something like:

PERL5LIB=$PERL5LIB:/Library/Perl/5.8.6:/System/Library/Perl/5.8.6
export PERL5LIB
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