jallen, just use a splitter on the coax out, run one to TV1 and the other to TV2.
You should then be able to watch TV1 on TV1 via your HD connection and TV2 via PIP on TV1. On the TV2 end, depending on how your TV there is set up, you should be able to see both TV1 and TV2. The TV I use as TV2 with my current setup (522 and 322) has 2 antenna inputs, so I have to split the signal again on the TV2 end. I have all my "stuff" interconnected in the house, with the 522 TV2 on channel 21, the 322 TV2 on channel 50, My 400-disc DVD Changer on Channel 62, and our video baby monitor on channel 64. With this setup I can view any of these video sources from any TV in the house, including viewing 2 sources at once via PIP or SPLIT if the TV supports the feature.
I'm really glad that the 622 will allow us to use something other than channel 3 or 4 for the TV1 modulated output, and have the option to turn it off.