I had to deal with something similar for a site I've worked on. This only works for compiled modules where your machine is binary compatible, though.

I made a directory under my ftp root called perl-mods. I installed the modules on my computer, then moved ftp'd up the ones I needed into my perl-mods directory. You must be careful to keep the paths preserved so they work right, of course. My computer ran Redhat 6.2 and so did the server, so any more complicated modules compiled the same. Modules that are just perl this doesn't matter for.

Then, in all my scripts at the tope I put a use lib /home/mine/perl-mods to use that directory. Of course, I know that is where my home is on the server because the admin was cordial enough to at least tell me that. If you don't know the path to your perl-mods directory, you have a harder time. I think you could put perl-mods underneath your cgi-bin (/cgi-bin/perl-mods/). Then do a use lib ./perl-mods I think that this would work since its a relative path. I know it works with an absolute pathname, and should work for relative too. Not quite the most secure I guess, but might be the best you can get.