I think AVElectronics uses one of those $100 tv tuners you see on eBay. They all have about the same features: 4-channel diversity antenna, aux. video inputs, reverse camera input, IR remote, etc., etc.
You will just need to find the video input cable that they use and also rig a switch like they provide to activate the TV tuner when you need it. I think the video input cable is more like a 3-way harness. That goes in between your NAV video output and your monitor.
Check on the TSX forums (I know you have a TL but, the electronics of both cars are very similar) for detailed install photos to get an idea of what the connector looks like. I think they have pin outs as well.
Another good source would be some of the auxiliary input manufacturers (aka Logjam electronics). I think AVElectronics uses a Logjam aux input for sound and they have a 3-way harness for video.
Just remember that as far as I know, you will not be able to utilize the touch-screen on your NAV for the computer - it is proprietary. Other than that, good luck and check out acuraworld.com & clubtsx.com for more information.