I think I may have found it -- go to http://members.fortunecity.com/irclescripts/scripts.html and there are three scripts that claim to include FServe functionality: Fserver, Halo 1.1b3, and MacPack 3.7.1. Hopefully one of them will have what you need.

I looked at Fserver and it downloaded in a format that only AppleScript Editor could open, so if you want to customize it, a regular text editor won't do the trick.

Hmm, just looked some more and there's a thread on FServe stuff at http://www.ircle.com/forum/viewtopic.php?t=10&sid=9061a8afb4a6d67209d4a473b18ed776 -- but it's not clear to me whether or not FServe is working in the current version of IRCle. (The guy posting there as Onno is the author of IRCle.)