If you read up on Roche limits you'll realize this either isn't so hard SF as it seems or at least Ceres have some form of harness keeping it together... Creating gravity through spin that would negate the gravity of the body itself and even more would most likely rip it apart. At least Ceres is probably big enough to not consist of one solid piece of rock, but rather matter cobbled together by gravity. Negate that gravity and... boom!