A while back a friend of mine had a 55 inch delivered. To my horror, the delivery guy just stood it on it's end an attached the stand. In the end, it did not seem to hurt the set at all. He's been watching it for 2 years now. However, it's still not something I would recommend.
If you can, call a friend to give you a hand. Or throw the delivery guy a few bucks extra, and have him help you out. While a 70 inch set is not overly heavy, it's a bit awkward due to it's size. It's much easier with an extra set of hands.