Ditto Ken:Woody, I think you're thinking of the B1.
The real B2 isn't even stable without its computers monitoring everything, so there's no way it would be stable in a passive configuration. However, you could do a clear extended airframe forward of the wing with some noseweight. You might need some clear vertical stabilizers as well.
CG in both cases needs to be ahead of the CP. In a rocket the farther ahead the better as it is only concerned with up and down, in an airplane the CG must be just ahead of the CP also known as the AC or aerodynamic center, basically the center of lift. Its a balancing act with aircraft since they fly horizontally, basically the the plane balances on the wings AC and the CG must be balanced by the tail elevator or elevons. Many flying wings have had rocket motors added and have flown well provided the CG is not shifted out side the acceptable stable range if shifted at all. Examples can be found in the Rocket Boost Glider forum.However, airplane CG/CP relationship is not the same as what's required for a stable rocket flight.