The difficulty depends on many things.
I would say PT post is the way to go, but install it over a post standoff past so water doesnt get trapped between the bottom of the post and whatever it is sitt ... read more
http://www.houselogic.com/home-advice/tax-credits/how-to-collect-tax-energy-credits/
I do not believe that would qualify. Only the materials qaulifies for the credit.