Paper bag. I went through all the same things in the beginning, and I realized the problem: my snake likes to eat in the dark, all by his lonesome. Just think about how your snake acts in the tank- if he doesn't see you, he roams around like it's nothing but as soon as you put your head next to the glass, it's all he can concentrate on.
So first, leave him alone, totally alone, for a few days. No handling, no peeking, no nothing. Then put him in a paper bag, like a regular lunch sack, with the pink. Fold over the top of the bag with a paper clip, put the bag back in your viv, and then turn the lights out and leave. Don't watch him. Don't peek in the bag to see if he's eating or eaten or not eating, just leave him alone for a good 20 minutes (it's not gonna hurt him if he eats it right away and then hangs out in the bag for awhile, that's why you put it back in the viv- the temps are good).
Please remember that it's *never* a good idea to leave a snake alone with live prey, so while this pink isn't gonna do any damange, this won't work once he moves up. I used the bag for about 6 weeks, and then moved up to a tupperware that he would go into, lid on, lights out.
I don't guarantee that it will work, but the paper bag in the dark and all alone worked when nothing- braining, f/t, live, heads, tails, scenting, etc. worked. It's not the food he didn't like, it was the situation.
Hope that helped, let us know how it turned out!
dara