Your best best is to go to a k-mart or walmart and get a 1 cup size Pyrex or Anchor brand cup and grab a teflon pot holder to hold the cup.
Cut the worms into small pieces and like and earlier post stated, nuke it slowly and stir often. When remelting the store bought plastics, make sure you have a fan or something blowing the fumes out.
The store bought worms really stink and smoke awfully bad but most have started out this way. Other than being able to make a bait that way, there is no comparison to using the plastisol that our supplier carry, so don't get discouraged.
If you're married and you want to stay that way, don't use your wife's microwave!