You basically want something like this:
Your TV will switch inputs between PS3 and HDPVR and send the audio out to the receiver, which sends it to your speakers.
Since your receiver isn't a 'proper' receiver (it doesnt have enough inputs to handle switching the A/V), and your TV also can't do the above, you need a new receiver. I was in the same boat as you, and getting a Pioneer VSX-1019 solved all my problems.