Once in Malcolm Corley's office, use your hand on the safe on the floor in front of the desk. Enter the correct combination gained from the part you previously viewed. To save you trouble, the combo is 154492. The safe opens and gives you a tape and a card. Exit to the right. Use the card on the card reader/slot. Inside the meeting starts with a cut scene. Once you get back control, use your hand on the projector Motor Lever once. Then use your hand on the Lamp Lever twice. Exit the room. A cut scene starts and the achievement pops.
Please note: I highly recommend making a separate save after getting this achievement. The end sequence is timed and has a couple ways to die. This will save some hassle later in the event you accidentally die during the end fight. There is an achievement for completing it in a single pass without dying. If you have a save you can reload from it, speed through the meeting cutscene, and then reattempt the ending.