That is the basically the same thing I suggested. I just mention a few extra steps for those who have not done this before. As stated though, the graphic you change has to be the same size (dimension) as the original. I have not tried to add other content to the theme. Just change the graphics. Works great. As long as you have a backup of the original file, go ahead and try it. Won't hurt. You can always delete the changed file and just copy your backup back to the original location.

I'm going to try it as soon as I get a chance. And I definitely appreciate the extra steps!