Simple...
Jump in the car head over to Aussie Mike and he will do it for you....
# Make sure you have the drill running at full revs before bringing the holesaw in touch with the tape on the glass.
# Most shattering takes place if the holesaw grabs or is not a full revs prior to contacting the glass.
# Drill the guide hole with a bit the same size as the holesaw guide bit. You may step up to this size with smaller bits.
# Then tape up as suggested, locate the guide hole and go at it slowly.
# Don't push to hard as the final part/section of the cut comes up quickly and if pushing hard you will push the hole saw into the hole bringing the flange in touch with the body around the hole. This will leave a burn effect on the surrounding glass - hence the tape.
Good luck