One of the reasons I've been reluctant to use modules in my code in the past has also been accessibility to CPAN.
in reply to Yes, even you can use CPAN
Typically my environments have been shut away from the outside world of the Internets, and it can take hours to follow and trace all of the pre-reqs for a given module by hand, downloading to my local machine, then uploading to the environment, only to find out that I missed one or two... wash, rinse, repeat for a few hours just to get one module finally installed.
How did I get over this? I carved out 6 gig of disk on a linux box in my environment and created a CPAN mirror. My friendly network admins open up the firewall for me when I need to update via rsync occasionally and I just point all my local boxes to that server internally. After my updates they close it back down. This way I can install modules to my hearts content as I need them.
Of note, I have seen software produces where an entire distribution of Perl has been included (HPOM/Dazel comes to mind) I imagine to get over the issues the above poster has noted....