Re-post here so we can find it easy.
2-1/8" hole saw
15/64" drill bit
Medium flat head screwdriver (to pry the rivets free)
1. Remove the mounting brackets from the windblocker. Without these removed you will have trouble fitting the windblocker and probably scratch your rollbar. There is enough flex in the winblocker to actually get it in and out from within the rollbar without too much effort.
2. Remove the mesh pouch. There are two screws on either side and about a dozen rivets on the lower edge.
3. Unclip the speaker leads and tape them to the amplifier so they are out the way while you cut.
4. From the backside of the windblocker. Using a 2-1/8" hole saw, drill a hole centered aproximately 8" from the outside edge and 2" from the bottom edge. Please double check the placement, because I am recalling this from memory. If I were to do it again. I would create a cardboard template the size of the windblocker, to get better placement of the holes.
5. Make two vertical cuts using a hacksaw to form an upside down U.
6. This next step requires some experimentation. This where the fun starts. Make 45 degree cuts to allow the bar to fit. See photos below for clarification. At this point it becomes trial and error. It's always better to cut too little than too much.
7. Repeat for the other side.
8. Once you are happy with the cuts, you can trim them with some black door edge protectors.
9. Attach the pouch with new rivets. I used 3/16" (5mm) short rivets. Unfortunately I was unable to find black ones. You will need to cut the webbing to the size of the rollbar holes.
10. You will need to modify the mounting brackets since the windblocker is more vertical than before. Cut the top most bolt off flush the the bracket. Drill a hole where the old bolt used to protrude. I used a 15/64" drill bit. I was planning to reuse the nut the from the orginal bolt, but found a the 15/64 hole was almost perfect for the bolt that I picked up at my local hardware store.
11. Now with the brackets modfied you can mount them to the car. You will mount the windblock after it was been positioned. (See step 1)
12. Mount the windblocker to the lower stud using the factory nut, thread a new bolt from the front of the windblocker into the hole you drilled in the bracket. You may need to redrill the upper hole in the windblocker to have it line up.
13. Replace the front covers on the windblocker and go for a drive.