While you might want to elaborate on what you mean by large, i.e. what size, and how deep the footings need to be, I agree with Ken, if this is the only task, there may be better choices out there. e.g. I know someone who bought a used telephone company truck, used it's large auger and put in piers very quickly, but he was only doing 30" diameter piers, and he had a bulldozer to level the building pad first.
All the best,
Peter