The main priority for grounding is to provide protection from wiring faults that energize metal surfaces that could then electrocute someone. If you are feeding power back into the house via a dedicated circuit, you should have a ground wire in that feed line which provides grounding to the generator. If using the generator as a stand alone power source, just use grounded cords to power the loads.

Thanks, HU! It is being used as a standalone with extension cords. The extension cords are all 3-prong - is that what you mean by grounded cords? Thx!

Yes, 3 prong.