If the reasons are paranoid, I wouldn't rely on downloading them from CPAN.

Download the modules you need, and put them in your own repository. This could be a repository with a CPAN structure (which you can have your CPANs Config point to), or a repository using your local package system. A yum repository with RPMs for instance. Another advantage of having a local repository, using your local package system, is that you can prebuild (compile) your modules, making installation faster.