I used a metal countersink, like you see inn the auction below, and a small pair of vise-grips to keep it from spinning. I think by using a countersink, there is less risk of having the bit jump out and digging into your carrier Either way, go slow...
http://cgi.ebay.com/3pc-TITANIUM-COUNTERSINK-DRILL-BIT-SET-1-2-5-8-3-4_W0QQitemZ6053694765QQcategoryZ50383QQcmdZViewIte m
