Using ChangeDesktop 1.3.1 (freeware), I've set up the "Preferences Application" with the "Change then quit" option ticked.
Next - using Dragstrip (Aladdin Systems Inc), I've set up a hot key for the ChangeDesktop application (not the Preferences application).
Now simply hit the hot key in any application, and the desktop changes. Keep hitting that hot key until you get a desktop image that you like!
I have also set up a folder of favorite desktop pics which I intermittently alter by throwing in duplicate copies of my currently favorite pics. This is the only folder I have selected in the ChangeDesktop preferences, though you can choose several folders if you like. For me it works better than OS 9's random selection at bootup.
[Sudo Editor's Note: If you do not happen to own DragStrip, it should be possible for you to do this with similar apps or even the dock!]

