I spent the time to extract XAMPP 1.6.4, you are correct, and that version would require a good amount of work to make it a workable Perl environment. The is no 'lib' folder included.
Unless there is some overriding reason, I would simply suggest you get on the current version, it has a well developed and rich Perl environment. If you are going to write and test scripts, take the time to upgrade (its a reinstall) -- I don't know what else you have in that environment, but working with Perl will be torturous.
If you don't have things to save, for sure make the upgrade. If you only have HTML files, save the htdocs folder to a location outside XAMPP.
If you have other projects such as PHP or MySQL databases, the process should not so bad. Dump the databases, and save all your settings in text files, Save your htdocs folder by copying it to a secure location and so forth.
I'm not trying to give you a comprehensive guide to upgrading, just saying to get your ducks in a row first
BTW, even if the installation does not require a shebang line, it serves another function - (hint) to tell you where to look for components.
The Good News:
XAMMP 1.7.3 comes with a fairly tricked out set of Perl Mods aleady in place. Some mods are windows or *nix specific (mostly ones for system functions), and won't work in all environments, so you may not find them in all installations. I was able to get every one of my apps running with no Mod's needing installation (which is not true for ActiveStates), other than the Webmin port which is dependent on one of those OS specific Perl mods that is not available in the current version 5.10.