What are your hot and cool side temperatures, humidity? I'd recommend adding a few crumpled pieces of news paper or paper towels to the tub to help make him feel even more secure. For four to five feedings I'd introduce a live mouse just to get him feeding regularly. With each successful feeding you can remove one of the pieces of crumpled paper.

After feeding 4-5 times consecutively you can try making the switch to f/t. If he refuses, wait another 3-5 days before offering again. I'd stay away from the oven, instead try using a hair dryer to warm the f/t rodents head. Also be sure to feed at night in a quiet darker room.

This is the advice I followed for my borneo short tail and he's pounding f/t like a champ.

Good luck and be sure to post pictures once he's settled.