Legacy BP5 steering wheel controls

Hello guys. 
 

I’m in need of some assistance with retrofitting the SWC on my 05 Legacy imported from Japan. It’s a prefacelift auto that came with the shift buttons on the steering wheel, I have bought prefacelift buttons and fitted them to the wheel but have no clue which wires to connect to where! I have attached photos of the connectors on the head unit and the steering column, any help on what I should wire to where would really help. I have fitted a Pioneer double din headunit too, if this makes any difference!

The 14 pin connector is the headunit side and the 8 pin connector is at the steering column.

Thanks,

Stuart