I'm not planning to take it as far as you are, tho

Basic functionality is all I need. My buddy put a 10" screen in his SRT-4, and put his heater controls in the glove box. I'd rather not have to do that. I'd like to run a 10" screen, so the heater knobs will have to go.
The way the Neon is set up the fan controls are basically off in the center, and the left 4 settings are for A/C and the right 4 settings are normal blower.
There's an on/off type setup for recirc/fresh air and I think I can integrate most of these functions by using relays. The other two knobs (temp and output position) are cable driven, so I'm kinda thinking I might need to go PWM and a couple of Servos. I'll have to research it more.
I'm going to remove the passenger airbag, mold/smooth the middle section of the dash and paint it. I'm going to mount the Mini where the airbag used to be.
The rest of the system will be finished out with some Pioneer TS-C720PRS components in the front, a Pioneer Premier TS-SW1041D, my Pioneer DEH-P790BT and 2 of my JL Audio "slash series" amps. I'm just going to keep the radio, because a) I like it, b) it has some decent signal processing ability, and c) it has BT handsfree built in. I also have an iPod interface and XM radio for it.
Essentially, the main plan is to install the computer to do music storage, playback, video and Nav (then my GF can have the Garmin Nuvi 750 back!)
I plan to mount some external USB ports in the ashtray area, and just use my portable 100GB HD to transfer new music and videos to the Mini, so I won't need access to the optical drive. If I change my mind, and decide I want the optical drive access, I'll modify the dash so that there is a slight peak, with a slot for access on top of the dash.
Maybe I'll even mount my original NES 2 in there somewhere
Jay