Got this info from a website called torque cars, it sounds about right.
"If you need to drill carbon fibre yourself you should cover it with tape and drill from the top down to avoid splintering, some people place a block of wood underneath but with a high speed drill setting this is not always necessary.When drilling carbon fibre panels be very cautious - check and recheck your measurements and use large sheets of paper as a pattern to double check".
Use a very sharpe good quality drill. Carbon is pretty good stuff to work with, i work in a bike shop and this is similar to how we would cut down carbon fork steerer tubes. We normally use electrical tape. Hope this helps