Originally Posted by
Speed of Sound
The three most obvious ones are, a larger diameter wheel (not feasible in current cockpit design), higher gearing (making operation take longer) or some kind of powered assistance (which defeats the idea of a solely human-powered mechanical method of trimming the stabiliser.)
Either Boeing ensures that the pilots can mechanically overcome an trim runaway, or they ensure that it will newer happen.
The later requires that the Flight Control System for the trim is upgraded to DAL-A.