part of it will depend on your tolerance - not to make light of the concept of being bitten and held by a large constrictor (or anything else). My approach, when bitten by something that wanted to hold on has always been to just wait them out. Yes, I frequently broke those rules about always having another person at least close by when handling the big guys. but the bites were rarely surprises. the worst (and most stupid, lol) was when I lost the "you are going in there" battle with a large, squirmy African rock. I had a set of cages occupying a walk in closet, and he managed to get his head between the top of the cage and the frame of the closet. DONE, it was all over, and I eventually gave up the (futile) fight and watched him disappear. He couldn't get anywhere, but I didn't want him coming out and wreaking havoc. In my infinite wisdom, I went down and defrosted a guinea pig... thinking I could lure him out.
It was a great plan, and would have worked easier if I hadn't lent my feeding tongs to somebody. (can you see where this is going yet?) I grasped the g.pig by the hind quarters, and pushed the head up over the top of the cage. Instantly, the rocks head shot past, circled down and grabbed my hand, and tried to retreat into the 3 inch gap over the cage. even if I had had a spray bottle, I couldn't have gotten to it. there was even somebody home that I could have called out to, not that she could have done anything. so I resigned myself to waiting. This sucked, because it felt as if I was being degloved (for those of you not familiar with the term, degloving is the removing of the skin from the hand...like taking off a glove). but as time went on, and my hand didn't go into the small space (picture me standing there, hand over my head, pulled against a 6' high stack of cages, while a large snake is trying to drag me in - its actually kinda funny), he came out just a bit to wrap a coil around my wrist. This sucked too, but it was the beginning of what I knew was my way out. after about 10 more minutes of squeezing and pulling, he came out a little farther to get a better grip, and I began working him out of the space. it took about 5 minutes but out he came. I sat down in the middle of the floor, and he almost immediately let go. I picked up the guinea pig (I had long since dropped that to the floor) and put it in his cage, then steered him in.
My advice to everyone - DON'T DO THAT!!
An

note - have any of you noticed that rocks, at least large imported rocks, tend to shoot past their prey, then hook back and constrict/grab in one motion...typically biting toward the rear of the animal. In my experience, this was a very common thing...at least with prey items ranging in size from large rats to 5lb rabbits. (yes, I had already noticed this when the above incident took place, and I knew I was in trouble as soon as I saw his head come out)