Reading back, I don't fully understand why you wouldn't want to tie up the ML. Why would you want to listen to an audio source whilst watching TV?
:)
As far as I know there is no way you can do it. I suppose if you were feeling very creative and you already had a link product in the room you could use a passive (or active) extra speaker kit and option program the link speaker to option 4 and the extra speaker kit to option 1 (from memory). This would be long winded and in my opinion pointless though!