My husband called about 6 weeks ahead of our trip to make reservations. We had serious issues figuring out where to go, since the instructions we were given were: stand by the trunk. The trunk is a 1910 Louis Vuitton steamer trunk, and was very cool, but there was nothing whatsoever to indicate that that particular point of the store was special in any way. Just very weirdly hush-hush and overly subtle.
Once we were retrieved by the hostess, we went through the history/waiver spiel others have described. In our group of six, we all agreed that it was interesting, kind of cool, and extremely awkward as you all just stand there as the various colors wash over you, trying to figure out if you're supposed to just leave on your own, or if there's a specific end point, or what. There is an end point, basically when the colors have cycled all the way around back to the deeper blue that you started with, about 10-15 minutes, the hostess will tell you your time is up, and you can go back and get your shoes.