You can set up the mozilla kiosk in kde and then tweak it and run it from windomaker. With a knoppix persistent home, the setup will stick.
At boot, I use: knoppix desktop=wmaker screen=800x600 home=scan noeject
These cheatcodes can be put in a custon boot floppy or cd. Note that if you use this trick, the word knoppix must be added at the start of the append, as in knoppix desktop=wmaker rather than just desktop=wmaker. Otherwise, it will just boot into kde.
Then, at startup, windomaker auto loads the full screen mozilla kiosk I have set up.
From a terminal in windomaker, you can run saveconfig; but it didn't seem to make any difference, so I don't use it.