For all that metal removal, I suggest using a big file, 12" or 14" bastard, with a wooden handle, wearing gloves. More effective and ergonomic this way, your hands and wrists will thank you. A passable handle can be made, if necessary, by drilling a hole in a scrap of wood and rounding the corners a bit with a rasp (I did this myself yesterday).
I'd love to hear some tips on filing from Mr. Church, and I'm curious about what exactly he uses for hot filing (and just how hot is it?)
Brainstorming a clamping approach, how about jamming a haft-like piece of wood into the eye, like a backwards handle, and clamping that down. Maybe in combination with clamping down another piece of wood that the top half of the bit is embedded in.