What operating system are you using?
If you are on Windows and have a USB port available, I would recommend checking out portable Strawberry Perl and put it on a USB stick drive. You can move the USB stick drive to a system with internet access to get more modules installed.
If you're on something like Linux, I think you can use something like CPAN::Mini to create a local "mirror" of CPAN on something like a USB stick drive and then move that to the isolated system to use for any CPAN installs. (Note: I personally have not used CPAN::mini before, so I would not be able to offer any assistance on how to use that module.)