It's been many years since I touched Perl CGIs on a Netscape web server on Win32, but if memory serves, the association that maps .cgi (or .pl) to Perl comes out of the Win32 Registry. This would put you in the same position as people having problems with <nobr>-T</nobr> under IIS, though the solution you need might be different. (IIS uses a "scriptmap" tree in the registry; Netscape might not.)
That's as much help as I can offer. Good luck.