ok well your common should be a positive from the battery it's called common cos it can be either + or - depending on the cars electrical system, so your yellow and yellow/black wires should be connected together and then put on a constant fused live from the fuse box so when u turn the car off the central locking will still work , then u need to find the wires comin from your key lock in the drivers door cos these wires are wot send the signal to your locking module find out witch wire does locking and witch unlocks with a multi meter and tap onto them with the white wire onto the lock side and the white/black wire onto the unlock wire, don't cut them otherwise your key won't work if u ever want to lock it that way, cut out n tape up the orange n orange/black wires so u can't get a short, and as far as i can see it should work, your best bet is to get a haynes though cos it'll have all the wiring diagram's u need and will tell u where to find the right wire behind the dash makin the fitting soo much neater and less hassle havin to take door card's off n trim, n if your keeping the car a while it will help u no end, with other mods n maintenance.

i'v not worked on fez's n no new ford's niether so i'm only goin off wot i no from my esco's i can't see it bein changed that much so i just hope i'v been able to help

Ryan