Yup, this has been covered a stack of times.
Everyone will tell you to push out the bonnet release cable grommet and drill it. Well, I couldnt get mine out no matter what I tried to do, so I ended up pushing it thru into the engine bay (well, its kinda behind the wheel arch) and running my 4g wire thru there, inside a piece of garden hose as extra protection. So the grommet is 1/2 out of its hole, with the 4ga going in above the bonnet release cable.
Pull back the plastic inside the wheel arch with the car on a jack, and youll see the grommet going thru there.
Have fun... it took me bloody ages and was very, very frustrating!
Scott.