After destroying the security stations and talking to him atop the tree, Slash tells you that he will meet you at the Space Elevator, but this is not true. You will have to find him again, this time in the sewers, where he is damaged and asks you to recycle a part. The doctor will tell you not to, but it if you want this achievement, then stand next to Slash and recycle any part you like. You will then get: this achievement, some dialogue and a few enemies to fight.