I have just put a reverse camera in a 2009 i30. Mine required a supply from the reverse light and there are two ways of getting there. One straight down the bumper to the left hand light cluster, or two at the centre of the bumper follow the number plate lighting cables.
I chose to do the later as I wanted the connections to be inside the car, but down the bumper would be easier, so I will explain that way.
Take out the rear L/H light assembly, which is easy, there are four screws on the hatch side of the assembly 3 are under little flaps.
When you remove these screws, the assembly comes away from the body, the left hand side is just push fit (3 pegs into rubber grommets). You can now see all the globe holders and wiring, the reverse light has orange +12v and black -ve wires.
On the car body where the light assembly covers, toward the top there is an unused grommet, you can use that to take the cable into the car interior.
The main wiring loom runs down the left hand side of the car, so you are now right at the beginning of it.
What I did was remove the parcel shelf L/H bracket (2 screws 1 bolt), then you need to take off the L/H rear door kick sill plate, to do that take off the L/H side seat base (1x 12mm bolt) now you can take off the kick sill. With a snake or curtain wire you should now be able to get the cable from the entry point to the rear passenger foot well, then from there it is easy just remove the front passenger kick sill and feed it through. To remove the front passenger A frame kick panel there are only two plastic retainers and now you are there.
If more access is required in the boot, everything in there is easily removed as they are held in with screws.
If you want any more info just ask, hope it helps.
