Next CSS/Perl question with XPP 9.3

Hello everyone: 

I have encountered my next issue with XPP 9.3, using CSS and Perl. I've created my css using the same name as my style bundle - in this case "basic.css". Then, I created a perl script with a simliar name - "", whose package name is also "basic". I originally had this perl file in the library directory for my publication. That works fine. 

However, I'd really like to include some other perl scripts that I've written in the past. Those scripts live in the \xz\perl directory. First, I tried to use statements like 'require' or 'use' to point to those files, but couldn't get that working (not sure when to use those, since I'm a newbie). So that could be part of my problem.

Then, I moved my file to the \xz\perl directory, but the compose process can't seem to find it there. 

In the css.pdf document, on page 1-4, it says that the perl file can be in the job directory, the style library directory, or "at the system level". I'm not sure what's meant by that, but I assumed it was \xz\perl. If not, then where should I put this file? Thanks!