One end of the strap screws into the base of the camera via the tripod socket, the other end threads through the standard camera strap lug. The third point wraps around your wrist and tightens with a buckle. By the looks of it, you could tighten the strap enough that it holds the camera without you needing to support it. US$16 from Brando.
Universal Ultimate 3-Point Hand/Wrist Strap is designed suitable for the SLR/DSLR, Camcorders and full sized Digital Camera. 3-Point Support Design (with Adjustable Wrist Support) – provides Ultimate Stable, Save and Comport for holding your DSLR/VideoCam when Shooting!!