Jim - I would take the time to follow/eyeball all your piping and draw a simple one line diagram showing the tanks, piping, pump and valves as they are in relation to each other in the system. Once you have this drawn it should be pretty easy to figure out what the valve positions need to be to accomplish what you want to do. It also helps you get familiar with where all the piping runs through your camper.
That said, I do similar to what MTBob does for winterizing, only I use winter windshield washer fluid for the drain traps and waste tanks. I also just hook up the air to the city water connection to blow down all the piping(there are several "how to" posts describing this in more detail on here if you search).
Good luck...