It's very difficult on 2006 and later Prius to interface with the MFD screen. As far as I know, none of the aftermarket products work with it. It's a rarely used video standard. This is discussed over on Priuschat in the technical section where they wanted the "Canview" to show on the screen, like it does on the earlier models. I don't believe they were successful, though I think they identified the interface name.

If you really want GPS, the least expensive and most flexible way to get it is to buy an aftermarket unit.

Pearl is a
2007 Driftwood Pearl Prius
Package "B" (everything but leather, nav, and rear camera)