I know that in my 300sd there is a way to bypass the neutral safety switch. On the left side of the engine bay, there is this black box that has four large wires going into it. If you take a piece of wire and touch the first and third one together with the key in the #2 position and the gear selector in D or N, it should start. If not one and three, try two and four, because I am not sure. I know that this trick only works for a while though, and when the switch is gone, you are done. Switch is only about $50 and is on the left side of the transmission from what I remember.