Don't drill. Dremel plastic locating pins off switchgear and use 2 sided gluepads instead.
Will allow for you to re-adjust later and won't compromise integrity of your new bars.
The controls that matter (throttle, brake, clutch) don't have locator pins to begin with, so you are only talking about the plastics. If you wan't to secure grips 100% surely you will have to get fatter barends to act as security stops.