You can remove the plugs in the holes with a door panel remover (looks like a BBQ fork). Or, I just pried them up with needle nose pliers, then punched the remnants into the hole (which will fall onto the ground below).
Installing is a ten minute job if you have a second set of hands to lift and place the cover. 15 minutes if you work alone. And an hour or so if you decide to re-key the tumblers to your ignition key.