There isn't a proper way to do it through Airbnb, @Dr--Foo0 -- unless the successful bidder has an Airbnb account and books at a deep discount once they've won, I suppose.
That sort of thing has to be done privately, with you blocking off the dates they want to come, and giving them those nights for free -- just as you would block off time for family to stay. Even so, the logistics can be a bit of a nightmare. The winner may want to change dates, for instance, or will really want a date that is already booked. They don't know how things work, and you'll have to stand firm. 🙂
I looked into once when asked, and kept hitting walls.
Good luck, though, if you do decide to do it.
