I drilled a set, and even had to drill one of the sides in a set of Honda bars -strangely, the switch was too much to the inside.
Not a hard thing to do. Just get the old ones as a pattern of where the holes go, both in distance to the end of the bar and orientation. Center punch, drill, and for the center holes use a file to smooth the sides.
I have seen switches filed and with the pin removed, because the previous owner didn't want -or know- to make the holes. It takes more or less the same time to adapt the switches to the handlebar, than the other way round.