First was to get the door off the car, and then remove the existing remnants of skin. The easiest way to do that was to just grind away at the folded edges… So, the left, right and bottom edges of the skin need to be ground down.
… but no need to do the top edge, as the whole support rail on the top side of the skin is replaced with the new skin… for the top all that is needed to do is to drill out the spot welds on the two tabs (I cut through them to seperate the skin, then drilled later). Also, there will be a spot weld on the side face of the shell where an L-shaped bracket near the door handle is spot-welded to.
Once the edges are ground away and the top edge sorted the skin will just lift off.
Back to the shell, there will still be some grinding to do to remove the lip of the door skin that was folded over. Grind away at the few spot welds along the circumference and the remaining lip will peel off.
Now for the new skin… this just sits on top like the old one. The edges will need to be folded over and I am waiting to get a decent hammer and proper dolly before attempting this.