there is loads of posts on here about mk4 amp wiring but ive never seen a certain answer of how or where but apparantly it can be done. you dont need to drill holes and I really wouldnt advise it.
apparantly there is a grommet near the bonnet release, look at the topic about 5 or so posts down from this one its called 'power cable problem'
there was another thread a while back too, try doing a search for it.
