I get the same problem.

The crowd I work with is bureaucratic, overly so. This makes it hard to install new modules, I dealt with this by getting my own box and getting rid of the sys admins.

That's not an option here. Talk to your sponsors, bribe your sysadmins. Get a separate perl set up (maybe):

/usr/bin/perl5.6/perl with libs underneath
/usr/bin/perl5.005/perl ..
/usr/bin/perl symlinked to per5.005 - change to 5.6 for upgrade.
[download]

Use the explicit path for your 5.6 scripts, you'll probably be able to leave them alone when 6 comes out unless you change them to use perl6.0.

My 2p. Standard caveats apply - I am no security expert.

PS Be nice to your sysadmin. They get flack for problems but no praise for installing new software. Life is hard...