If necessity is the mother of invention, then this idea of using a Prius as an "emergency generator" to provide power for your critical electrical needs is a creative solution. Not being an expert in using a power inverter and how to hook it up--I'll stay away from the technical details.
I know this is pretty basic, but I've seen many a person die from the improper use of power generation equipment. Therefore, remember the car must not be parked in a garage or other enclosed building with the engine running. Carbon monoxide is a silent killer.