Don’t know if this will be helpful, but I searched all over for a way to cut t-hole slots for hanging pictures and frames. It needs to plunge to a quarter of an inch, and then nibble forward, back up, nibble forward, back up, etc. This is if you don’t want the hassle of first cutting a quarter inch pocket, then following up with the keyhole bit. This code is for 1/8" depth of cut slot cutters. The bottom of the cut is only .25" deep so this is safe for .5" material.
This code slows the plunge to 5 ipm, and overrides the feed rate to 10 ipm. It goes .1" forward, goest back to zero, and creeps forward another .1" until a 1" slot is created. It then returns to zero and lifts out the bit.
Worked great for me. You just zero out right over where you want the circular hole to be. The slot will be cut up (away from you) from there. My machine is set for inches. You may need to do a little translating. And you’ll need to secure your material a little better than double sided tape.