Did you end up giving it a try? If so, I'd be curious as to whether you've found the correct wires in the factory harness to tap-into the steering wheel controls, as I'm trying to install a joycon device.
I just put a carputer in an 08 9-3 Aero. I put the computer in the back left-hand corner of the trunk where the Bose amp was (replaced it with a real amp), and a 7" touchscreen in the dash. I had to fabricate my own dash for the screen as it's hard to find dash kits for these cars (and was impossible just 3 months ago).