Quest: X-13 Attack of the Infiltrator.
Note before attempting this quest you need the upgraded sonic emmiter (thanks nasty grandma) from the X-8 facility which is the quest High School Horrors (see spinal tapped for details).
This is a quest you receive from dr Klein at the start of the dlc. Once you arrive at the X-13 facility you need to pick up 3 pieces of the stealth suit and equip it on your character then head over to the test terminal to begin the test. you need to reach the safe without being seen by the robots, if you are caught then head back to the terminal and start over, any doors you unlocked will reset as well. Stealth boys will increase your chances of getting through but are not necessary, once you reach the safe grab the documents then the achievement will pop. (its not necessary to wear the suit to start the test, thanks UnknownAvatar)