Hi! When I first got my ball python, he was eating live but he immediately made the switch for me.
I usually thaw my mice under running cold water (the safest way to thaw meat) and warm it up with a hairdryer. The first time he took it as soon as I put the mouse inside his tank but the second time, he didn't take it so I had to do the zombie mouse trick. The way I do it is I wiggle the mouse around and bump his body a tiny bit (not near his head). Usually when the mouse touches his body he goes for it.
I find that when I'm warming the mouse up with the hair dryer, my snake smells it and immediately goes into strike position. It has worked for us so far. Good luck!