Two things.
1. I wouldn't use the hook to take him out. That can create pressure points and hurt him. I would use the hook to let him know you are there and not feeding him. You can tap him or gently rub him a few times to get that message across.
2. Gentle and repeated handling should get him used to it. Start with 1-2 minutes for a few weeks (2-3 times a week), then go to 3-4 minutes, and then to 5-10 minutes.
Most snakes do not "like" being handled, and BP's are prone to stress, but he should adjust with repetition and being gentle with him.