Boneguru,
If you don't have the chuck that holds the case by the rim you can make a jig by cuttin two pieces of hardwood (1x2) to the same length, clamp them together and drill a hole between them that is just under the diameter of your case at the rim end, then while you have a case in the hole (that is half in each block) align what will be the bottom and drill 1/4 inch holes on either sid of the case for 1/4 inch bolts and nuts.
To use it just put the case in the jig, tighten the bolts, put the jig in the drill press and drill the flash hole to the proper diameter.
PaulS