Punch it, Pull it, or Fill it?

If you have to absolutely pack it, use a reinforced filler such as duraglass, bondo hair etc. then skin with regular filler. If you have a welder and a pair of vice grips, weld a big ol washer on the end of the adjustment screw, tack a screw or a small tab of sheet metal on the car, clamp on and use a slide hammer with a little hook to pull it.