How to set the greeter / login wallpaper *before* anyone is logged in?

[mkleehammer]

All of the discussions I've seen say the login / lock screen uses the current user's wallpaper, and that is working for me. But what about the wallpaper before I am logged in - there is no current user?

The code has a background.jpg, but is there a way to point the greeter daemon at a different, root-accessible image?