During the Chinese GP the TV showed a very cool device the Ferrari mechanics were using during the pit stops. By it's size and shape it was obviously a pressure cylinder with an electronic control unit, and an air valve on it. THe TV commentator stated that it was developed for last year's one tire set per race rule. The mechanics programmed each one individually, and when the car came in to pit without changing the tires, all the mechanic had to do was press the air valve against the wheel valve to adjust the pressure, up or down.
Real nice, real simple to use. Just program in the pressure desired, and when activated, it will add or vent pressure to the tire as required. It probably took about three seconds to use, nice and simple to use.