The bonnet release wire hole in the passenger footwell. It comes out behind the sound-proofing
You can squeeze up to 4awg cable through there, though I would have thought it will be easier to push the end through from the inside, unless you want to try and push a cars length of wire through from the engine bay!!
Also, undo the coolant resrvoir (2 bolts) as it will make it much easier to get your arm down there and get the wire up, and unclip the power steering reservoir it might give you a bit more room.
Be warned though, you have to force your hand down there. A few scratches will ensue.