Instructions
Complete the 'You Gotta Shoot 'Em in the Head' quest and return the three keys to Mr. Crowley.
Take back the keys you gave to Mr. Crowley at the completion of the quest. If your sneak level is high you can attempt to steal these from Mr. Crowley or else kill him and loot his body.
Visit Fort Constantine in the Northwest. A Senturion robot guards the gate, so you will need to destroy it to enter the fort.
Explore Fort Constantine and dispatch any of the robot guards that are roaming the area.
Enter the CO Quarters and destroy the robot inside.
Loot the open safe in the CO Quarters to find the Launch Codes.
Unlock the door at the back of the CO Quarters using 'Ted Strayer's Key' which you obtained from Mr. Crowley. Enter the locked room to proceed to the Launch Control Bunker.
Interact with the computer terminal in the Launch Control Bunker to launch the missiles. This is an average locked terminal, so your character must have an average science level to use the controls. The missile will fail to launch and the computer terminals will explode, however your character will gain experience for the successful computer hack.