Sorry, but another vote for leaving it alone. If you're stuck on particular bugs, or if modules you use regularly have been upgraded and only work on later versions of Perl, that could give you the basis of your case for upgrading. But why 5.10??? The fact that you're talking about only getting the features in 5.10 suggests it's more of a "latest and greatest" kind of thing than any real business need. Perl 5.10.1 fixed a bunch of bugs in 5.10, and there are two major releases after that, with 5.16 not too terribly far away; so upgrading to 5.10 is just pointless.
Still, if you just want to install a more recent perl, perhaps pointing out to your bosses that you're three major releases behind, you could also replicate CPAN on a local machine, and install current modules from there.
But if all you want is say and given/when, you can replicate something quite close to those quite easily.