To tell perl that another directory also holds modules/scripts that you are using you put in:

use lib '/dir/where/stuff/is';

What this does is that it pushes that directory into @INC and Perl looks in the directories that are contained in @INC for the modules that it needs. So if the module/script you are using doesn't find what it needs in the base directory where the script is located then it will look through the directories that are in @INC.

Hope this answeres your question,
BMaximus

update: Ick, slight mistake corrected.