To edit the menu bar.. you would edit he ubbt_registerednav.tmpl and ubbt_unregisterednav.tmpl files.
I have a chatroom (remotely hosted) from chat-forum.com. I think it's around $20/month. I've managed to integrate it into a threads page, and use the thread username when they enter chat.
You can see if you'd like.
www.measurection.comlogin: testing
password: testing
After you are logged in, click "Chatroom" at the top.