Before entering the asylum there are two lower entrances. Use the left entrance. After passing the lava filled room you will go through a couple of tunnels with a monster.
When you reach the room with the stacked up boxes climb them. Above them there are some rafters. Climb on top of them and go to the one closest to the door that you entered the room through(you can jump over it instead of trying to land it perfect). It will say Cheat Active. Now you have it.