Originally Posted by oneclick

The LBS will use a big (BIG) dollar tool to remove 2mm from the bb shell (should be 1mm each side to keep things symmetrical), It is not that difficult to do but you don't want to buy the tool.

If you have a Dremel or similar and your crank arm (either one) has a flat face parallel to the bb cup you can mount the Dremel with a cutoff wheel on the crank arm and take a few passes until you have a slot almost through to the threads. Then you take everything off and out, knock the cut bit off and tidy up with a hand file.