Individual, infinitely-adjustable lap bars and some form of safety strap. It is unclear at this time whether the strap in question will be a seat belt (ref. Magnum, etc.) or a lap bar safety (ref. Raptor, Mantis). The lap bar is T-shaped, coming up from the floor between your legs and extending across your lap; the lap bar is equipped with a grab handle, and handholds can be found on the rigid surface in front of you, and possibly also on the sides of the seat.
Of course, none of us coaster nuts will need the grab bars, right? :)
--Dave Althoff, Jr.