Old Library

IIRC, what I did was pull off the center trim, right at the top of the hatch
opening, partially detach the C-pillar trim and lower the rear of the
headliner about 4"-6".  It was somewhat difficult to get clear access to the
nut on the bottom of the antenna, but I used an adjustable wrench to break
it loose - it wasn't too tight.  After that it was pretty straightforward.
One thing to be careful about is that, IIRC, the clips that hold the
C-pillar trim are in little slots and can get misaligned from the tabs on
the trim.  Just push them back into place and push the trim back on.  A trim
pry tool helps pop everything off nice and neat.

HTH,

Luke
'97 GTI VR6

I replaced the gasket on my '98 a few months ago. The top trim
piece in the hatchback area comes off fairly easily and you can pull
down on the headliner just enough to get a long wrench in there (I
think it was 19mm?). The headliner itself is pretty thick and fairly
durable. Though I wasn't pulling down very hard. it would be a hell
of a lot easier with 3 arms but I managed. Good luck.

~Mike
98' GTI 

When I did mine a month ago, I used my red bentley's instructions and just
dropped the back part of the headliner so I could get  a wrench in and undo
the large nut holding the whole fuba assembly on.  Pretty easy actually.
You'll see.

Mike
98 GTIVR6