you can put them in a pillow case or something and just walk outside swing it and pop it against the wall. Not to hard you you can have a mess on you hands. then just dangle it in the cage about 4 or five inches away from him.
If you can't handle that then F/T is the ticket just pull one out of the bag and put under a heat light (not the microwave as once again rat is not easy to get out of a microwave LOL .. hey it been tryed) then just present it in the same way as the preekilled