FreeFSWP can set an image as fullscreen wallpaper on your S60 3rd Mr and FP1 machines.
FreeFSWP needs to sign before installion. You can sign it with your dev cert. If you don’t know about cert and sign, please visit www.symbiansigned.com and follow the instructions to get FreeFSWP Open signed.
...read more about FreeFSWP on the donwload page