This is why I'd prefer to have it on a separate page (also) rather than integrated into the forum. The forum will get fairly cluttered in my eyes, with players, radio stats, and disclaimers everywhere. I don't see any apparant space for this.
Personally I hate pop-ups, regardless of what they are. I find it most appropriate to have a mini-site dedicated to the radio on radio.www.offtopic.forum. This would include the radio player, a request line, time table etc.
Don't play anything with a **** load of racism though, we swear on the forum, and if they found out about the radio they clearly visited the forum first.
We'll just put a small disclaimer or something to be on the safer side of things.