Well I don't know what ya'll have in mind for this but, if youre wanting to code your own flash or java chat client that could be time consuming. My suggestion is there's a chat client on the market called 123Flash Chat. I'm sure atleast one of the admins knows what it is but if not, its a Flash/Ajax chat client that has multiple skins and allows some pretty cool site integration like being able to interact with the user database and when a user clicks the room to enter it auto detects the username and signs them in under that so there's no altering and creating inappropriate names and allows people to realize who is who. It can be coded so that its incorporated on the site to where you can't even tell it's not part of the site itself. What you could do is have it setup as a link under "WGT Community" and when clicked takes you to a page with room options.. you could have rooms such as "General Discussion", "Help and Advice", "Friendly Game", or "MPC".. or something along those lines. Then when they choose the room it auto-logins as their wgt username into the room.
It also has features where you can assign moderators for muteing and banning users.. which would consist of wgt admin of course.
Don't know if youre willing to use 3rd party software... but its an idea.