An old post, but one whose recommendations seem to work well – especially the part about installing as a non-root user – if you’re faced with an inflexible packaging of a system Perl that you don’t want to touch, like an RPM install. (Not needing to worry about things like this most of the time [...]
Use the -o flag to portupgrade to replace the perl5 port with a the perl5.8 port:
# portupgrade -rR -o lang/perl5.8 lang/perl5
After the upgrade (this is applicable after any Perl ports upgrade, such as 5.8.8 to 5.8.9), run the perl-after-upgrade script, first in test mode, then in fix mode:
# perl-after-upgrade
# perl-after-upgrade -f
Fix any errors highlighted by perl-after-upgrade, and reinstall any required packages. [...]