It's possible to make a script that performs a /whois on everyone who joins (usually a minute or so after they join to count out users who part quickly), and if the channel is in the RAW 319 response, you can kick that user.

On @*:JOIN:#Hatfields: .timer 1 60 if ( $nick ison $chan ) WHOIS $nick

RAW 319:*: if ( $2 ison #Hatfields ) && ( #McCoys isin $3- ) && ( $me isop #Hatfields ) { ban -u60 #Hatfields $2 3 | kick #Hatfields $2 Get off my land! }

- Raccoon


Well. At least I won lunch.
Good philosophy, see good in bad, I like!