its been fairly easy for me for the most part to switch them over. Most of my collection doesnt care if its live or ft they just want to eat a good meal. Although i do have a few that will only eat live still working on them making the switch.
feed a small live prey item and when the snake is still "hyped up" dangle that f/t in its face and see if it dont take it, ive seen that work more than once. but dont do that alot it can present problems with back to back feeding.
My first ball was so picky he would NEVER eat F/T but Chumley, my current baby will actually go back and forth. He fed live mice at first, refused a few meals, took F/T mice with no dance, ate a live small rat (they were out of frozen) then went right to F/T rats!