Why can't you use Perl 5.10?
If you end up installing the latest Perl from source, you can then force your interpreter to use a specific version by using use version_number .
If the version of Perl you are using is compatible with the modules (no reason why it shouldn't if the Perl version is newer) then there should be no problems.
It's generally a good idea to avoid modifying the system Perl- sometimes the system is tweaked to expect/work with whatever quirks and bugs the particular version of perl comes with and you can break things in unexpected ways by messing with the system perl.
True, but the OP did say he was learning Perl. Hence my suggestion to use the system Perl.
I forgot my favorite linux flavor: CrunchBang with lxpanel instead of tint2 (although that may change if I get to configure tint correctly).