So, let me start by saying that I haven't had a chance to pull apart my dash to look at the cable coming from the steering wheel yet, as I'd like to pull it apart as few times as possible, since it's pretty much a *****. That said, I have a 2007 Scion tC that I'm installing a CarPC into. I obviously want the five buttons on the wheel (vol +/-, track </>, mode) to work with my carpc. Before you refer me to the Joycon or Arduino thread, well, I'm trying to not spend too much money, and was hoping to make a parallel or serial cable to hook to them, and do it all in software. I was wondering if anyone has any information on:
Steering wheel wire harness pinouts
Programming for parallel or serial ports
Any idea of how feasible this his or if it would take more work than it's worth.
I basically want to wire them as a simple human interface device like the media keys on a keyboard. And since it has a mode button, if I could program that to be kind of like an alt+tab button, or switch between different screens in RR, that would be extra credit.

Too long; didn't read
OP wants to wire steering wheel controls to parallel or serial port instead of buying a joycon or arduino, and would appreciate all help in doing so. Possible payment for any exceptionally good help.