Just did mine when I installed my Velossa Big Mouths. Only on the corners though. I used a Dremel with a cutting blade around the entire outside just far enough in to cut the back piece off while still leaving the honeycombs, then I used a carpenter saw to cut the rest off using the dremel cuts as a guide. Was going to use a hacksaw but felt more comfortable with a rigid blade. Did a quick sanding on the back to clean up what I could and then used a fine-tip fine grinder on the dremel and a fine file to clean up the rest. Sorry I don't have any pics of the process or having it off the car but I took the front off and then removed the grill from the bumper (mandatory IMO to do this).
Came out great IMO. There are a few imperfections if you look really close and every honeycomb is not perfectly uniform. But you're not really gonna notice it. Filing and cleaning it up was the longest part. Everything else was easy. Not sure how I would do it if you wanted to do the mid-section as well. Drill each one would be a pain in the dick IMO. I'd probably just Dremel around it and then slowly cut in until that section comes off.