A friend of mine did this, kinda as a part of his weird charity mission to relocate some gators not long after Hurricane Katrina hit. His wife is an experienced animal control officer, and he really wanted to assist for the experience of it.
He says it didn't take much strength to keep a gator's jaw shut. The tricky part is straddling the dangerous animal so that they can't whip you the ground with a smack of their powerful tail. The jaw closes much more powerfully than it opens, and my friend did start to question his own sanity after seeing the old owner had missing fingers.
