I decided to post this as people ask about it on occasion and why not share? thats why we are here!
So, i bought small (1/4") circular magnets in 2 thicknesses 1/16th inch and 1/8th inch. I drilled countersink holes in the helmet mounted earcap with a drill bit the same size as the magnets in 3 locations. I put superglue in the countersink holes and press fit the 1/8th magnets in them. then i did the same for the removable part, using the 1/16th magnets. You have to be careful on the removable side because its very thin so you just need a slight countersink.
To get them to line up..i just put dabs of black acrylic on the magnets on the helmet side and then lined up the earcap and "touched" it in place so it would transfer the paint to the outer cap.
Mine isnt lined up totally perfect, but its close..i could have taken a bit more care and got it more even but i was rushing it for an event lol