I just tried 4 quick downshift pulls and it worked. The pulls seem to be buffered and then the gear number on the display updates as it reaches each new gear. I'm assuming you could probably do more, but I didn't try. I've been just double tapping up and down on the gear lever for the reverse and drive selection from park so I guess it's basically the same thing.
This actually makes me wonder if the transmission has the ability to skip gears maybe depending on drive mode, how fast you shift, and what you are doing with the car. The kick-down feature mentioned in the manual says that if you go to full throttle it will automatically select the lowest appropriate gear so it sounds like it goes straight to that gear. I'm still early in break-in process so haven't tried that yet.