Facing 505 Parnassus Avenue, turn left and cross the street at the first crosswalk (at the stoplights)
Go straight ahead to the bank of five elevators, press the down button, and take any of the them to level P1
Exit the elevator towards Irving Street and prepare to take your first right down a hallwall
When you have an option to go left or right, go left down the long hallway until you reach the end and follow it to the right