Is this different to the chat window on ustream?
No, the IRC channel is the backend for that chat window. (The only real difference is that IRC is, of course, text-only whereas the chat window adds some icons, for instance a little question symbol when someone types 'Q:' -- people use that so Dave can spot their questions easily!)
logged in, but i got need +v msg from the channel. its been years since i played with this. hope i'll be around on 4am.
I believe you need to have a ustream account to get voice (+v) -- if you log into IRC using your ustream username and password as your nickname and password (or, if you don't have that option, typing /nick username:password once you've connected), the server should grant you +v automatically.