At the start of the mission, once you gain control, head down to the bottom floor and toward the exit to the yard. Just to the left of the entrance before you leave the cell block is an inmate who you can talk to. He'll give you a multitool if you give him some alcohol. You can get bottles from any number of places, but one is to search the cells on the second and third floors, focusing on hidden compartments near the door. You should find a couple of bottles. Trade one to this inmate to get the multitool and unlock the achievement.