I put mine in a sandwich bag, place it in a pan of lukewarm water for about an hour, then hot tap water for another 30 minutes. This should thaw the rat completely. You can tell when it's thawed because you will be able to push the belly in. Then, pick it up by the scruff of the neck or the skin on its back with the tongs and heat it up with a blow dryer for about 40 seconds or so. It will also help if you use the blow dryer to blow the scent towards the enclosure while you are heating it up. This will let the snake know it's feeding time. Do the zombie dance about 3-4 inches in front of the snake. Good Luck...
Here is a video that may help...
YouTube - 8 Ball Pythons - Feeding Lessons