Is there a way to associate this with a style so that it will be set when the style is selected?Only way i can think of is by writing a script, and use that script as your style's rootCommand.
The script would set the background, write a new .xtdeskrc file, and restart xtdesk. If xtdesk can be started with an rc file specified, it could be done that way instead of writing a new file each time.
original here.