Silvestri have adapters for all fittings Phase One currently produce which is:
Hasselblad V
Hasselblad H
Mamiya 645AFD
Contax 645
They also produce a one-shot release cable so the camera back will work by shooting once with this cable instead of twice to generate the wake up signal and a second time to do the actual capture which would other wise be the procedure with this type of camera.
Visit their homepage for the adapters here:
http://www.silvestricamera.it/eng/prodotti_eng/digital%20accessories/digital_accessories.htm