[Notice: Thread resurrection from >3 years ago]
Hello EvilHeart. You'll be glad to know that as of several months ago, the ability to do this has been made easier, but how you accomplish it will depend on the network server you are on and which features they support.
Some networks support a form of EXTBAN which may allow for direct banning of a gecos. Freenode allows this via $r:gecos?goes?here and $x:*!*@*#gecos?goes?here ban masks.
Alternately, you can write a script that loops through each $nick(#chan,%i) and examines $ial(%nick).gecos for a matching pattern, banning that $address(%nick,N) when a match is found.
In order for $ial(%nick).gecos to work, a /ialfill #chan must have been performed at least once since you joined, AND, the server must either support CAP extended-join or you must manually perform a /who $nick on each person as they join the channel (expensive). So your results will vary depending on the network capabilities.
It's pretty straight forward from here, so I'll leave you to the actual task of scripting it so you may achieve a sense of accomplishment.
