Im quite sure you can use a sprint BB on Alltel or Boost CDMA , i flashed a
sprint Mogul 6800 once is it possible with the Blackberry 8330

Now that Alltel is Verizon, I doubt that you can put a Sprint BB on that network. Verizon will only allow their branded devices on their network. If the ESN or MEID isn't in their database, it can't be activated. Flashing can't change that.

Doesn't Boost use the iDen network? If so, it would have to be an iDen (Nextel) phone. Can't get around the laws of physics or technologies.

To my knowledge, Verizon is STILL not activating Alltel devices on the Verizon network. And if that's the case, there is absolutely no shot that a Sprint device will work, or vice-versa.

Boost is not CDMA, it's iDEN, or in other words, prepaid Nextel.