There is a commercial product out called winchbit. Before it came out, I went to a machine shop and had a square piece of stainless steel cut down to have a round end to fit into a cordless drill. It worked great. People always talk about needing a heavy duty right angle drill for this job. I had a Freedom 38 which has a large dacron main with 5 battens. I used a Sears 18 or 19.2 volt cordless drill, and got multiple hoists per charge out of it. Total cost, very little (probably around $100). The bit I made up only had four sides, as opposed to a regular winch bit, but it never was a problem. Flatten the rounded end that goes into the drill to get a better grab of the bit.
Ahhhh if I had only patented it, I would be (minimally) richer.