Dano -
The procedure is very simple. Of course you will have to remove the rear seat in order to remove the trim panel (also very easy). My only tip is to lightly scribe around the regulator mounting hardware in order to install the new regulator as close as possible in position to the original regulator. This should minimize any adjustments you might have to make. If you have access to a 1968 Fisher Body service manual, the procedure is listed step by step. Good luck!
Paul