separate alternating walls for individual themes

[Spartan616]

Is there a way to have alternating wallpapers for separate themes? How could/should I go about doing that. For those that don't understand here's an example. Let's say I get an app like LauncherPro and I either find or make a theme that I like, but I want alternating wallpaper for the 2+ themes that I have. Is there a way that I can have one folder of walls work with only one theme and another folder work with another theme?