Hey, Did the mod last night, I would say the hardest part is getting the vents out and having the balls to cut the wires. Works a treat tho, all done in 20 mins.
Only point I might add is there are 2 wires that look pink, dark pink and light pink, it is the light pink one that you connect to the white with silver and the dark pink (red) is the handbrake that is earthed (loom side remember).
If you can wire a standard cd deck then you can easily do this mod, dont be scared, it'll save you a fortune and it is easy as with a bit of confidence.
Thanks for the diagrams!