i managed to drill an igo-s - the pin is short, but any SS drilling is a PIA and you need to use cutting fluid ideally (so ofc i used vegetable oil -nm)
I leave the insulator alone, although that's possible and i use a cutting wheel on a Dremel to work from the bottom of the removed centre pin up to a point i marked with, say a black marker pen. I hold the removed pin in a vice is all. It doesn't have to look pretty although if you are OCD, then not getting a lovely smooth little channel will irritate you. Sorry!
Getting the pin in and out of an Atomic is easy enough - it pushes out from the top with a little assistance from a hammer! To put it back in i used the hammer too - but i removed all the screws so as to not damage the threads on the other two negative posts.
I'm running dual coils with 26g which hit a rather pedestrian 1Ω and it's not bad!
T