Does anyone know where I can buy the adapter for a Pentax *istD2 digital SLR so I can use my old 645 lenses?

I have an older Pentax 645 camera and bought my new *istD2 just recently. One of the reasons I purchased the *ist was because I can "supposedly" buy an adapter for the use of my old lenses. I have yet to find the adapter. Also, the internet company where I bought the camera said they didn't realize there was an adapter available.

It's back-ordered at B&H, but this is it: http://www.bhphotovideo.com/bnh/controll...
Here's some more info on the adapter: http://photo.net/bboard/q-and-a-fetch-ms...