This is a little bit of html I changed to work with a TT changing wallpaper. It will change the TT wallpaper by the season Spring - March , Summer - June , Autumn - September and Winter - December and the time of the day Morning - 3am , Daytime - 11am and Night - 7pm. Just place the .html in the right folder and the wallpaper folder in the right place. Just click the link below for the .zip.
The pic above is the one set for summer daytime. There are 12 different color pictures to change through.

http://putstuff.putfile.com/55028/5195566