I have created a very minimal OS X install on a USB stick to use as emergency boot media. Basically what the install is, is a clone of the Mac OS X Install DVD with the installer and packages stripped out. I have my own launch daemon starting an app launcher when the install starts.
The problem right now is that the wallpaper is just a blank gray screen (like the background you get when you first boot OS X and you get the Setup Assistant). I would like to load a custom wallpaper. I've already tried using NSWorkspace's setDesktopImageURL:forScreen:options:error method. This method works when using a complete install of OS X, but not on my minimal one.
The one example I have of a wallpaper being loaded in this minimal interface is Apple's LCA.app (In the OS X Installer DVD/System/Installation/CDIS). It starts the language chooser when you boot the OS X DVD, and also loads a custom background wallpaper. I've taken a look at the binary for the app using otool, and I see that there are some methods for loading a wallpaper in there, but they seem to be private methods used by the app.
Does anyone have any ideas on how to do this? One possibility I can see is just loading a layer behind my app that acts as a wallpaper. Is it possible to do this?