You should have 2 black wires in the large grey plug - these need joining together, the other wiring changes are purley for reverse lights etc..... if your car isn;t starting with the 2 black wires joined then i would suspect a problem elsewhere....
there are 2 other wires in the large grey plug need to be joined into the 6speed reverse sensor which is the 2 wire plug on the back of the gearbox. As it says in the article there is only 1 plug that plugs straight into the actual box, the other plug is as mentioned and everything else can be taped up.