http://www.ft86club.com/forums/showt...hlight=yobiwan
Look at post # 14 and 22, I dont think he has a dedicated thread for his tablet build.
My approach to a nexus 7 in dash would be to get audio from the usb port which runs to a Digital to Audio converter that has its own volume knob and can fit in the bottom storage compartment near the push to start button. DAC should run to an amp which goes to speakers, that way you dont lose audio quality by using the tablet as the audio source.