Or you could try alternating directions as you go up. I got it: the staris go left .. but maybe at the top of a flight you could kind of side step to the left and then spin around to your right (instead of spinning left every time) and head up the stairs? It would probably make the workout harder, by killing your forward momentum and requiring more coordination, agility, and balance ... but why would a CrossFitter want to work harder and develop those three physical skills?
Of course, this would depend on the exact size / structure of your stairs, but it was just a thought ...