I haven't ever had PS, but I have feedtrained RES which have similar tastes. So has Bill Cody.
I started out with earthworms, then transitioned through freeze-dried krill to floating pellets. Switch over between stages gradually and realize your fish will have to be a little hungry to try something new each time you progress toward pellets.
Cody does terrible things to earthworms and pellets in a blender for his feedtraining and is at least as successful as I have been. Just messier.