I have posted this on the australian altezza forum, but thought someone from nz toyspeed might be interested...
My ultimate goal in this was to be able to play mp3s, and have some kind of interface on the factory screen. I didn't want to mess with the factory console.
With this install, you could potentially put a dvd player in ur car, or anything that has 3 rcas - 2 for audio, and one for video.
This install cost less than $250, and I now have 80gb of storage for mp3s, movies, and pictures. I can easily upload more media to my car, or plug in another AV device at will if needed.
The ideal device based on my requirements was the mediagate mg-25 Hard drive based media player:
http://www.airlinktek.com/english/prod_mg25.htm
This harddrive based media player allows you to add mp3s, pictures, and movies and play them on any tv via composite video.
Before the HD could be installed, I had to find a way to get video and audio to the factory screen and speakers. Since the TV tuner was of little use to me (since I don't really want to watch tv in the car....), I decided to hijack its video and audio outputs, and put the HD video/audio in their place.
First, I had to remove the panels to get to the tv-tuner:
Once the tv tuner was unbolted, I had a look at the wiring. On the left hand side of the tuner was the aerial plug. No need to worry about that. The next plug had nothing plugged in - so not sure what its for. The third plug was video - luckily, composite. This means theres no need to mess about with rgb + sync. Just two wires - +ve and -ve. The final plug has 12V power (always on), 12V (ac switching), ground, few others, and the left and right audio wires.
It's worth noting at this point that the TV Tuner I have is model number 86010-53020. I think the one that cpufix has is 86010-53010. Not sure if this is a is200/as300 difference, or because my car is a 2001. However the wiring does seem to differ slightly...