I just looked up your headunit on Pioneer's website... hard to tell for sure because their install instructions are confusing, but it looks like they list that the only wires you have are...
- all the speaker wires
- black = ground
- yellow = constant 12v
- red = ignition 12v
- blue/white = amp or antenna
Could that be right? If so, you won't be using a lot of the PAC wires.
As far as the speaker wires, just match those up to the harness... FL, FR, RL, RR... or however you are planning to run the speakers and/or amp. I do see that your unit has some specific instructions if you are trying to run a sub directly off of the headunit.
For your black = ground, you can actually connect it to BOTH of the black = ground wires on the PAC harness.
For your yellow = constant 12v, connect to the yellow = Battery +12V on the PAC
For your red = ignition switch 12v, connect to the red = ACC Output on the PAC
For your blue/white = amp or antenna, I'm pretty sure you need to connect that to the blue/white = amp turn on input on the PAC. Reason I say that is because when I talked to PAC, I told the guy that I am running an aftermarket amp off of the headunit and not using the stock amp - but he told me the harness still needs the amp turn on lead regardless. So I split that line to the PAC harness and to my aftermarket amp.
Other than that, you won't be using any of the other harness wires, if I'm understanding your setup correctly. You did mention steering wheel controls - for that you need to use a small screwdriver and turn the little dial on the blue steering wheel control device to "7" - which is for Pioneer... controls come preloaded so you won't need to program them as long as you set the dial. Then you just plug the steering wheel control device into the harness and the other side has a 3.5mm jack to plug into your Pioneer. You won't use that blue/yellow wire on the steering wheel control device.
The other wires on the PAC you apparently won't be using because you don't have the options... Vehicle Speed Sensor, Parking Brake, Reverse Output = that's all stuff for in car video, back up camera, etc. It is strange you don't have an orange/white illumination wire I think.
Hope this helps!