Do Miche bottom brackets require a special tool, or is this one damaged?
The OP notes: "Shop agreed that this part is defective, was happy to swap with another one. FWIW the guy there said he'd never seen another Miche bottom bracket with this issue. –  spacemanaki Mar 29 '14 at 21:56"

I just tried a google image search to see what they look like because I'm not familiar with Miche. The pic isn't perfect, but does give an idea that the splines don't have a taper on them like yours. Glad you were able to sort it with your LBS.