As others have stated before: The primary controls for a snap roll are elevator and rudder. Depending on the geometry of the aircraft, some aileron may be needed. I have never had an aircraft that needed full aileron to perform a snap roll.
When you get used to snap rolling you may find that the elevator input should preceed the rudder input by some small amount.
Also, when the snap roll gets going it is often advantageous to reduce elevator input by a small amount. How much has to be determined by trial and error. Reducing elevator input minimizes the speed loss assiciated with snap rolling. This is especially so if one wants to perform a double snap.