On a '91, the switch unit comes off w/o removing the door panel. As I recall, all the buttons pop off, then a plastic c-clip around one of the switch bases. The escutcheon then slides off, allowing access to two screws retaining the switch ass'y. If you DROP the screws, the door panel will have to be removed.
I have removed the door panel, but remember only it wasn't hard after doing a message search here for the procedure.