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I don't think so. I asked the same Q a few months back:
https://www.lfgss.com/comments/13546681/ -
I recently bought a J&L Ceramic BSA30 BB but ended up using a RaceFace BSA30 instead; The RF cups are 10.5mm wide, same as most other external-cup BBs. The J&L cups seem to only be 8mm wide, so if you can find a J&L for 24mm spindles, you might be able to compensate for the extra 5mm of BB shell.
I wouldn't use the actual bearings the J&L BBs come with though: cheap ceramic bearings can be worse than bottom-end steel bearings in terms of ball-roundness, and the inner-race could score the spindle if the bearing stiffens or seizes. Should be a standard size and easy to replace, the bearings in mine didn't take much pushing to pop out. The inner diameter was also under-spec such that I'd need to at least freeze the spindle to get the bearing onto the right bit of the spindle.
edit:
This is the J&L BSA30 I bought: http://r.ebay.com/jjaRAc
Looks like the 24mm/GXP cups aren't slimline: http://r.ebay.com/4UnCq2
Is there any way I can run a ht2-style road crankset (for 68mm bb) on a 73mm bb frame? (assuming the cranks clear the frame) or is the axle too short? (could use either shimano or fsa)