Between playing the game over, and over, and over you should have this nailed easily. However if you want it quicker all you need to do is start a game on easy, kill the first three guys and then rubberband the controller to keep Alicia moving. I’ve found it easiest to move her to the right side of the building on the right and have her walking into the fence. Then go to sleep wake up and end the level. DO NOT DIE. The game only counts the time between checkpoints and ending the game. So if you die before you reach a checkpoint or end the game all that time will be lost. That’s why I suggest doing it this way because as you walk around the next corner you get a checkpoint. Do this a couple nights and the achievement is yours.