First you get some really strong friends. Then you hold the dial steady, and have them rotate the safe.

Just a little humor.
Do you have any pictures of the safe and the dial? There were different locks used over the years, and pictures may help us determine the correct instructions. Without that info, we don't know if the four number combination is three wheels and the number where the dial stops when the bolt is retracted, four wheels then turn it until the bolt retracts, four wheels and then turn the handle without feeling the bolt retract because the boltwork is attached to the handle, or even which direction to start dialing.
Gordon
Just when you finally think you have learned it all, that is when you learn that you don't know anything yet.