Sure Antony. If you look, from the rear of the car, with the boot open, you can see the existing factory harness on both side of the boot going into the passenger compartment.

The easiest way to do it is to move one of the seats all the way forward, and start removing the trim around the seat belt fastening area. You'll have to pull the carpet on the rear interior firewall out of the way a bit as well. You can then use a fishing tape pushed from the interior to the rear.

I found it a lot easier to do this when I had the seat completely out of the car, as it makes removing the carpet and trim a lot easier. Also gives you access to the factory wiring trays running along the floor of the interior.

I suspect in your case moving both seats forward and removing the carpet and trim on the rear firewall will give you the access you need if you are mounting your rear display where the factory display is...

 

Some pics HERE.

 

Thank you very much for your quick reply John!!!
I actually havent decided yet on the display position matter yet. Ii will be more oem if i put it where it is supposed to be and at the same time it will save me the time and trouble to take the cable to the dash but it wont be as easily viewed unless you turn your head each time you back up. There is always the beeping of course.What is your opinion?

 

Well, I actually like the OEM position - when you are reversing, you are looking in the rear view mirror, so with the OEM position, I can see it by shifting my head a bit. Tend to use the sound more anyway, though - so I'd not be horribly fussed if it was somewhere else I guess.

 

I suppose i ll go with the oem position then. The next part of the problem will be to enter the sensor cables in the boot from the bumper and the actual connection on the backing up light, so that it will work each time i shift to R. Do you have any ideas on these matters?
Thank you again!

 

Very useful thread! It actually makes it all very easy!
Thank you!!!