I posted this (link below) for removal of the Mk3 head unit somewhere on the forum. Basically to get at the rear of the head unit you follow the short clip on Youtube. Just one awkward bolt up the side of the head unit to get at all the rest is easy stuff. But some folk have been able to get at the rear by going up through the glove box opening, I never managed it. You are after plugging in the aux cable into the what may be termed as a cd changer port on the lower rear of the unit left side if looking from the front, near the aerial jack conn.