Never underestimate the power of Poster Putty!
And this totally depends on the design of your windows and your siding on your house..... hang them from above the window, on fishing line. You can try to find some edges or corners to hang or hook some fishing line. Then you hot glue the fishing line to the backs of the "boards" in their locations in front of the window. Then you hook/anchor the fishing line below the window. The reason to use this idea, is so the boards move with the wind. They'll be in place, but a good breeze will make them shake and move, getting some natural sounds as they bump the house.
I intend to use the Command Hooks for Xmas lights above and below the windows, and tie the fishing line to them.