you just slide the windscreen down and put the screws through the top holes on the flysceen but the second on the mounts. Then if you like it you drill a new set of holes in the mounts to line up with the new position of the bottom holes.
they use the top holes of the flyscreen in the bottom mounting holes if im not mistaken. I think this means that its only attached by 2 bolts though unless they drill and tap a couple more.
Buellchick has a taller touring CF windscreen dropped and I just screwed in the top screws into the bottom screw location, and just used small nuts on the lower bolts for looks.