I planned to receive it some way in my perl script without using a webserver...

What's your problem with HTTP? Is that really what you are trying to avoid? Please tell us what the issue really is.

which sends its output via a html form with post method

Sends it how? Via HTTP? As long as you use HTTP, you'll need an HTTP server (aka web server).

If you do want to use HTTP, it doesn't mean you have to use apache or IIS. It could be something written in Perl (say like HTTP::Server::Simple). Your script doesn't even need to be persistent if you use inetd.

If you don't want to use HTTP, you'll have to find some alternate means of communicating the request from JS on one machine to a perl process on another machine. Your options are quite limited, unless you have limited setup. Perhaps you could provide us with more information about your setup.