I machine wash cold, line dry. The wax wore off one pair after a year or so, which was fine with me as it left me with a pair of solid black jeans. Another pair (my expensive R13 crossover jeans) I wash as rarely as possible and I haven't noticed any change in the wax.
(It's funny how my different jeans need to be washed with such different frequencies. I assume some combination of fiber content, skin-tightness, and fabric weave.)