No one suggested my eventual "solution," so it is probably wrong. :(
I realized just because the servers have 5.6 on them doesn't mean that something like 5.14 or even 5.20 can't be installed and run on them. So I installed perlbrew and told the person who needs to run the script to use have perlbrew use perl 5.18 to run the script. Other than some major annoyances with setting up perlbrew, it seems to be working well enough.
If I did have to write something to run on the older Perls, I really like the ideas put forth by Athanasius and Corion. Also I guess BrowserUk came the closest with the "Don't do it" answer.
Thanks again for the help