The process I used is as follows -
Drill through from the inside of the van to the outside every time there is a change of direction using the inner skin as a guide (i.e. holes at both ends of corner curves, changes of angle on the skin etc)
On the outside of the van using a straight edge join up the dots with a permanent marker so that you have a cutting guide that follows the inner skin shape
From the outside of the van jigsaw between the holes following the lines. Use window suckers on the metal work so that when you make the final cut the panel doesnt fall and damage your van. At the curved corners cut a straight line diagonally between the drill holes. On some of the windows you have to cut through the inner skin where the stiffener is but the jigsaw goes through it fine.
Using hand snips trim the metal all around on any bits that are higher than the inner skin. Also use the hand snips to cut the curves at each corner
Using a retractible knife (the ones that you can snap the blades off with) cut into the rubber bead all around between the two skins getting the knife between the bead and the metal and remove all the beading
Knock on the U prifile edge trim using a rubber mallet - Some people put sikaflex between the skins at this point. I dint it on the first window but didnt bother with the rest as the U profile holds the skins together without it
Once the profile is on prime around the outer edge of the trim using the dinitrol primer. Also prime the glass with the activator.
Offer the window up to the rubber and ensure it sits well against the U profile. You may have to knock the trim in or out in places
Once you are sure its a good fit apply the adhesive and then offer up the window - Make sure you have a strong adhesive gun for this. The cheap £5 ones wont cut it, I learned this the hard way. I ended up with a £15 one out of screwfix which handled it well. Also get a bit of heat into the adhesive tube too - I had mine on a radiator when I was doing the other stuff.
Thats basically it
Oh one other thing. Buy a container of panel wipe off ebay or amazon. Its a life saver when you get adhesive on the paint (which you will). With panel wipe it just wipes straight off. Also use rubber gloves as the dinitrol is a nightmare to get off your skin once it dries
