it comes out right at the top of the dash behind the airbag
to get to it you will need to remove the glove box which also means you need to remove the front section of the centre console as there is a hidden screw holding the glove box in
when you have removed the glove box you need to pull the white fluffy material in front of you to one side and look right up to the top of the bulkhead and you will see the grommet
i am doing a mk4 on saturday so will do a quick guide and post it saturday afternoon