Are you talking about the picture shown in the splash screen as the game loads or within the game? I don't know if it could even be done in the first case, but even if it could, in either case really, it would most likely involve File System accessing.
In the latter case, the load screen wouldn't show up for any period of time anyway, so that's probably not what you want (but if it is, it could probably be done using inventory and no scripting at all, or a small amount of scripting making it easier)
In the former case, I've really got no idea....Unless you did some file renaming using the File System Object on the names of the pictures you're using.