Pacific Accessory Corporation (PAC) makes steering wheel interfaces (SWI) for about any vehicle and stereo combination. You just need the one for Pioneer/Sony (PS) instead of the one for JVC/Alpine/Clarion/Kenwood (JACK).
What I'm trying to say is you need the PAC-SWI-PS instead of the PAC-SWI-JACK which you can order just as easily as the other one. I've got one in my 370Z with a AVIC and it works fine.
Pac-audio.com Products | iPod Integration for your car and More by Pac-Audio - Connecting you to the future
I ordered mine online from here:
Discount mobile electronics, Bluetooth hands free, cellular repeater, cellular amplifier