New modules can be downloaded at CPAN: File::Random, allthough I'm not really sure you need a new module, most modules that ran under 5.8.4 will run fine on 5.8.8.
Wether or not you can create new directories on your server will depend on the administrator of that server; here your webhost I think. Just try it and you'll see.
However, generally it's a bad idea to include hardcoded directories in your script using the 'use lib' pragma. (any move of server/version would mean you need to change the script) The preferred way would be to let the webhoster include these packages in their perl distribution. Don't know if that's possible though.