I've looked at this and it's not as easy as the whims people have. First off you need an ODB to USB interpreter, that's pretty easy there a few on the market. Next you need to make the driver to read/write ODB signals. Now the fun really begins because ODBII isn't all the same, everyone has their own version and extra command set. Are you ready to license all of these? The final problem is the ODBII polling rate which is pretty abysmal. 2 variable polling isn't bad, 3 starts to get sluggish, and anything over 3 gets really pokey. It's about 50-100ms a poll, so you figure how much info you want. Another big problem is ODBII is on it's way out and CAN-BUS is here.
The AVIC has a pretty limited backend so you'd have your work cut out. Personally I find it's pretty easy to use Auto Enginuity through bluetooth on my HTC Diamond when I just want to log, or break out the laptop, my tactrix cable and open ECU when I want to play. Bluetooth get you all excited? Too bad the AVIC's BT isn't a windows BT stack it is parrot BT hacked to work with the NAV system.
For a product to work well you need it to be something noone else has done, do it cheaper than the others do it, do it easier than the other's do it, or do it better than the others do it. Since ODBII scantools are on the market you'd have, and there are some cheap ones that work very well without having to hack a $600 nav system it would be a long road.