Maybe I'm misunderstanding your question, but I believe the answer is you don't need to.

Adding directories for @INC when building Perl does add them in defaultly for the system, but you don't need to concern yourself with site_lib, vendor_lib, etc, etc, etc. The build process takes care of all of that for you.

All you should need to do is add the various directories you want ADDED to the typical system wide @INC.

Hope this helps...