I have a 1997 VS Berlina that didnt come with the factory cd stacker. I was told that the wiring for them was pre-installed and that all you needed to do was tick the box when it was brought new. I have looked high and low for the wiring and cant find it. Is what i was told correct or do I have to go through and take the stereo system out an put a new cable in. Any help with this would be awesome....Cheers