Right, good.
First of all, the new cable clip that comes with the kit is too long. It's a plastic c-clip that keeps the cable away from the window by affixing it to the door frame. The one that comes with it is longer than the existing one and fouls the window.
I couldn't use the existing one as it was too large to keep the new cable in place. The new cable must be a smaller diameter than the old.
What I did was break off the existing one and scrap the new one. Neither are any good to you. I then drilled a small hole in the frame just below (5mm) the hole left by the existing clip and tie-wrapped it. It doesn't move when the window operates so can be tight as you like.
Secondly, the cable crossover on my new one was opposite to the crossover on the old one. This worried me as it looked like it would foul the window. In practice, it doesn't and it makes no difference so ignore this.
Lastly, when removing the mirror cables from their retaining clips, carefully cut the fabric tape - don't try and remove the retainers. When refitting just use 2 small cable ties on the existing clips, one either side as they are lipped.
The above will mean nothing to you at this point, but they will as you come across them during the job.
I'll PM you my number in a minute, drop me a text if you get stuck and I'll do my best to help. You may not need to as its actually fairly simple if you are methodical, but it saves a panic if you get stuck.
Dan