I finally finished the program to read the button presses on my Steering Wheel Controls. The complete story behind this and the instructions can be found here Most of this is repeated in the ReadMe file included with the setup program.
The setup for the program can be downloaded here
You will need DirectX 9 or greater to run this since it uses Direct Input. The MFC dlls it uses are included in the setup package.
If you want the source for this program (MFC / Visual Studio .Net 2003) e-mail or PM me.
This program was designed for and tested on a 2003.5 Infiniti G35 Sports Coupe w/ BOSE Sound System. It *should* work with any car that uses steering wheel controls that work by varying the current read on a power line when a button is pressed.