I've written WEBChat to specifically address the problems associated with firewalls/proxies ... You're welcome to contact me and we can work out a simple script so each member automatically enters a VMF chatroom on webchat with their name as default.
I'll be implementing a preferences and "plug-in" support (i.e. the dice are an early attempt at working in custom designed plugins for all sorts of uses) sometime in the next 2 weeks. I will also be moving it fro Resin to BEA Weblogic and using a "push" model to get rid of the refreshes.
WEBChat is free for all VMF members to use at their leisure and will defeat any firewall/proxy issue -- all your members need to do is click a link! This would benefit me since I would get some beta testers in the deal and you because it will be a good alternate/primary chat forum for the guys/gals.
There are a few URL parameters supported right now for customization:
refresh=? This will allow you to change how fast the chatroom updates in seconds (min 2)
room=? This will allow you to join/create different chatrooms
name=? Changes your name
colour=? Changes the colour of your text, must use hex RGB style (i.e. FFFFFF)