That was back in 2002 before I even knew what a Dremel was or heard of one
I used 3 small files, flat, round, and triangular plus a junior hacksaw blade and as far as I can remember used the original clip for the H2 bulb to hold it in place.
Never said it was easy, but I had plenty of time as I was out of work due to an altercation with the front wheel of a truck
where bike escaped, but I didn't
Sizing was trial and error with a blown H4 bulb. Remove the rattly bulb cap put in the H4, mark it with marker, remove bulb cut and file holder, bulb back in mark some more and do the same again.