Take RER A (towards Marne-la-Vallée or Torcy),
Get off at station Noisy-Champs (20 min from Gare de Lyon),
Exit at the head end of the train, then on the right (exit #3 named 'Bd Newton, Cité Descartes'). Taking the right exit is very important to avoid walking too much.
Walk 400 meters to the campus entrance (if the security asks, say you are visiting).
Walk another 400 meters to the Coriolis building.
IMAGINE is located on the 4th floor (with the elevator on the left after entering).
My office is B404, the first door after getting out from the elevator.