I very confused. In the OP, I understood that you could do it using prncnfg.vbs. Now you say you can't.

If you can't, there's no much I personally can do. You'll need to find out how to do what you want to do at the system level. Once you do, we can help you implement it in Perl.

is there a Perl way to add a "local port"?

If Windows can do it, Perl can do it.