Interesting... hope you realize the Volt is a compact car and has less interior room than even the regular Prius (aka liftback) let alone the Prius v wagon.
See Specs tab of
Compare Side-by-Side.
I recall someone mentioning plug-in kits for non-plug-in Priuses. I wouldn't bother.
However, the Volt is admittedly much closer to an EV than the PiP due to the PiP's limitations (e.g. limited range, max speed of 62 mph (IIRC) in EV mode, being hard on the go pedal = ICE turning on, etc.)