I haven't installed a TOM, but read on a thread a long time ago that Warmoth drills a grounding route to the hole closest to the control cavity; if you pay the $10 charge they install the grounding wire.
I've installed a number of Wilkinson studs, and you can use the same technique as ferrules; strip the end of your ground wire and run into the hole then insert the stud and start pounding it in with a small hammer carefully; once it's started/true cover with a folded washcloth and carefully hammer the rest of the way in, checking frequently and being careful not to go to far and hammer body wood.
Good luck finding the correct metric size, thats a super fine thread. screw the stud into the ferule most of the way and use jacks hammer idea
with a piece o hard wood or tough plastic on top of the stud to soften the blow. It should go in snug and not require so much pounding that you screw it up, when in doubt, think twice.