I had a similar problem. I purchased a little Pastel from a breeder I trust, but he and his other Pastel sibling weren't yet feeding. The whole clutch had shed, and everyone but the Pastels were on feed. The weather was getting really bad and cold, and I've had great luck with getting picky eaters to eat, so we agreed to have him shipped over. He didn't eat for weeks, despite my every attempt to get him fed. I had to assist feed, which went just fine, though he was a stubborn little guy about it. Two days after his first meal he was incredibly active, and four days after I offered a mouse hopper. It took him about ten minutes to get comfortable, but he grabbed it, killed it, and swallowed it down. I'm elated about how it ended up, and that he is now (knock on wood) willingly eating on his own. For reference he was 43 grams on arrival from the breeder. I hope it goes well for your little guy, but don't be discouraged. It takes some snakes several assist feeds before they get the idea. Good luck!
Cheers,
-Matt