Forester steering wheel controls to Pioneer headunit

Hi and thanks for reading. My problem is as follows.

I have a 2007 Impreza WRX Hawkeye (I know this is for Forester's) and I'm trying to add a few mod cons, with my current project being steering wheel controls, which I have to start from scratch.

I've bought a nice 2007 Forester Momo wheel from ebay with the required buttons which I'm wanting to connect to a Pioneer head unit using a 3.5mm jack, with a CTMULTILEAD.2 Universal Stalk Steering Control.

I've identified the wires connecting to the audio controls on the wheel.

The black wire is used to earth the system to a point on the back of the air bag. After this I'm uncertain and beginning to guess, I think the red and blue are power, if this is the case where can I tap in to get some current or will the MULTILEAD use the 3.5mm jack to power the SW buttons like headphone controls?

This leaves the orange/silver and white/silver wires on the wheel, looking at the MULTILEAD it requires 3 wires either; purple, green and orange or keys 1, 2 and GND. 

If I'm right GND will connect to the black ground wire, orange/silver will connect to key 1 and white/silver (or reversed) to key 2 and the power from the 3.5 mm jack. If I'm wrong, can anyone advise me of what to do or what tool I may need to find out what each wire actually does?

Thanks in advance for any advice, it's greatly appreciated