Not only will you ruin the pad, but you'll shorten the LOP of your gun. Just but a new pad with the same thickness as your old pad but with the contoured shape
It is not difficult to fit the new pad to your gun. YouTube has several videos showing how it's done.
In the alternative, it is a routine and relatively inexpensive job for your local Gunsmith
If you want it "dead nuts perfect". Send it to Tron
I just bought an MX3 that has a Kickeez pad. The LOP was about a 1/4 longer in the center of the pad than my slightly concave pad on my old BT99+. I didn't like the inconsistency I was getting in my mount with the flat pad. I took the pad off and using just my vertical one inch belt sander, medium grit, easily ground the face concave until it matched my BT99 pad. Took about 3 minutes and cleaned the edges up with a finer piece of paper by hand. Looks fine, works great, piece of cake.
I would think if you don't have a vertical sander puttinga drum sander head in your drill and putting the drill in a vice would work just fine to shape the pad.