It doesn't matter if *.div files are associated with DivX; the game doesn't use Windows' file associations, and you can still open the config.div file in notepad to edit (just not by double clicking).
You can try adding config.lcl entries in the config.div file, but the game may not recognize them there (each file has an expected format).
I've changed my game resolution in the config.div file, but never needed to do anything with the settings in the config.lcl file.
