If twitch supports having channels be invite-only and doesn't let people inside the room see the uninvited trying to come in, you could have a lobby channel set up that whenever someone joins the lobby and they're not on the Troll list the script automagically invites to the 'real' channel. The problem with this method is that people would either need to manually join after they're invited, or have mirc set to automatically accept all invites which isn't a good idea or they have a script in mirc like:
on *:INVITE:#RealChannel:{ join $chan }
Of course that alternative works only for viewers using mirc, which probably isn't everyone.
