I also don't see what's so hard about IRC. You don't even need an IRC client. There's plenty of applets out there. You could even build a relatively simple chat window with the instructions embedded in the page next to it. I'm not even talking about the complexity that Lange has.

http://webchat.gamesurge.net/?channels=tf2.mix.nahl
http://webchat.gamesurge.net/?channels=tf2mix
http://webchat.gamesurge.net/?channels=tf2.pug.na
http://webchat.gamesurge.net/?channels=tf2.pug.nahl

Type !need to see list of players.
!add [classes].
Wait to be picked.
Join mumble.
Join server.

Start with a helpful applet page like that and build up to a system like Lange has that would be pretty and fun.