To make this achievement less of a drag, occasionally throw rocks near enemies before you decide to kill or move past them during your playthrough. When I actually decided to go for this achievement it only took a few tries because I usually threw a rock before I engaged an enemy.
Also, I don't think it matters if you kill an enemy or not after distracting them with a rock. As long as they move towards the rock, look around, and return to their original position, it should count towards the achievement.
111/117 games completed (including DLC)