I'm about to start a project and thought I would document it here for anyone that's curious..
Having a car with its own wifi hotspot sure opens up the possibilities.. This setup removes the lockouts on the unit and allows you to access the "cargo cam" input and use it for any video input you like (I choose a chromecast so I can stream over wifi and screencast from android mobile devices as well.
This is the "contraption" as I have it ready to put into my car.. Its a custom harness from customtronix, a chromecast, a HDMI to RCA converter and a usb power cable with both a mini and a micro end on it. I will update this thread after I get it all installed and show the steps.
Here are links to the items needed to perform this modification.
Customtonix.com for harness and software update
Google Chromecast HDMI Streaming Media Player
(HDMI to AV Converter Metal Case (VHD-168))
1.5-Feet RCA Stereo Video Dubbing Cable
Micro USB / Mini USB Splitter Cable
4Pcs Auto Car Radio Door Clip Panel Trim Dash Audio Removal Installer Pry Tool
Here is a picture of the setup as I have it ready to put into my car (tape and tie wraps just to make sure nothing ever wiggles apart).. more images of the install will follow in a couple days after I get it installed.