Assume for a moment that you have to wire an adapter between two 220v plugs. One plug is a 4 pin plug, with a ground, a neutral and two 110v hots. The other plug is a 3 pin plug, with a neutral and two 110v hots. If the source of our energy is through the 4 pin plug, and the load is on the 3 pin plug, is there anything wrong with wiring a jumper wire between the neutral and ground lugs in the 4 pin plug? (I.e. in the 4 pin plug, you'd then have two 110v hots, and 2 ground/neutral pins tied together).

Does your analysis change at all if the source of the energy is a generator with a 4 pin 220v outlet on it?