You can use CPAN::Mini to create a mirror of CPAN (but including only the newest version of each module, which reduces the size to something around 1GB). Of course that needs to be done on a machine that does have internet access (but you have access to such a machine, otherwise you couldn't ask on perlmonks :-).

You can put that mirror on an USB stick, and configure the urllist of your CPAN client to use that mirror.

I personally use such a setup even when I'm online, because it speeds up module installs significantly. Works pretty well.