Every Mac client I've used since the beginning of time will auto fetch every user's address in a channel. They all do it the same way. Sending 5 /userhost commands, each /userhost command specifying five nicks too look up. 30 second wait between each set of 25 nick look ups, and once the entire channel has been checked, it waits 300 seconds and then starts again (for obtaining both away and oper status).
My script does this... but really... I think it's time mIRC does the work.
