It should be possible. Expect at least a 2 MPG drop in fuel efficiency, maybe more depending on the tires you purchase.
The European version of EPA testing showed a 1.8 mpg difference between the 15 wheel Prius and the 17 wheel Prius.
I'll take the lower mileage, those hubcaps are ugly!! They look like there off of a pontiac sunfire! The V wheels just look so much better on the GEN III!
Driving habit is a more important factor as there are a few members with II-IVs in the Los Angeles area reporting 34 mpg (in fact, my wife gets around that if she drives it). I'm averaging 50 mpg (computerized) and my best to date is 54.8 mpg (52.0 mpg actual). Sure, I'd get higher if I had the 15 wheel Prius but not with less careful driving.
I don't have the factory V wheels and tires, but I did swap out the 15's to the Scion tC 17's. Since the swap, I have been averaging around 46.85 mpg compared to 50.97 mpg with the stock 15s (these are actual calculated numbers instead of the displayed MPGs).
I would love to have V wheels put on my IV. Though, I remember reading somewhere in the pc that it's not a good idea. Don't exactly remember what the issue was, but it might have something to do with the steering ratio. Maybe someone could enlighten me again.
