Instructions for installing a slab door and door frame. The following video will show how to install a slab door, or a door that is not pre-hung. A slab door can be very difficult to install when compared to a pre-hung door installation. Most people will purchase a pre-hung door to install instead of trying to cut the hinges out and match them with an existing door frame. However, the following instructions will guide you through this hard process of installing a slab door and door frame/jamb. The following installation uses the Quick Door Hanger Kit.