When I fitting mine earlier this year I simply unplugged a square shaped 4 pin connector block which is located just inside the side skin by the fuel tank. However, I believe the connecting method can vary according to model, age or personal modification.
The problem then is…… With such a large connector block you can’t pull the loom through the old rubber mounting block. My solution was to carefully cut this away and retain for later use. With the loom freed up you can easily mount to the CF and drill without disconnecting any wires. I recommend you drill some drain holes at the stage.
I used the old rubber mounting block, cut down and superglued back together with the loom passing through the centre hole, as a sealing grommet for the 25mm (approx.) hole in the wing. Again, the size of hole can vary depending on who built the car, but IMHO it works much better than a grommet. They look the dogs.
I can mail you pics if interested.
Phil
Summer Lightning Haze