What should be noted about the melee attack is that it is awful. You can spend forever sitting there stomping one enemy and they will continue to crawl after you, so you need to find small and/or exceptionally weak enemies to work on this achievement.
The easiest enemies to kill with melee attacks are those small pods that sprout the single tentacle, because they are among the few enemies that die from one melee hit. On my second playthrough, I had a ton of stasis packs and health packs saved up and I simply used stasis on, and stomped, thirty of them at the beginning of Chapter 5.
In the Medical Imaging Bay (where the yellow tube taking an MRI of a corpse is) there will be one of those annoying, screaming guys that shoot out the aforementioned pods. Without stasis it takes impeccable timing to stomp the pods without making them blow up, but adding stasis to the mix, it becomes simple to kill it easily and move onto the next while risking none of your precious health.