The diving itself is simple -- click to jump out of the airplane, hear the same silly "yeeeehaw" soundbite whether you're the male or female diver, then use a right-mouse-click to go from a spread-eagle position to a tuck, movethemouse left and right to perform various tricks, and finally click the spacebar to pull the ripcord.
These devices seek to move beyond themouse and physical keyboard, letting people communicate with their gadgets by gesturing, using sign language or, in the case of Skinput, tapping on their hands, fingers and forearms.