theres 6 screws on the sy mirrors, 3 on the ty
sy: 3 keep the trim panel on, remove the three screws and slide the trim panel out of the way (down along the mirror arm)
then thare are 3 torx screws holding it in.
remove those, and install the ty mirrors. carefull not to overtighten and crack the plastic. the ty mirrors have a different set of torx screws, black and longer. two are fairly easy to get to, and the third, you have to severely bend the mirror 's break-away section to install.
nothing to do from the inside (ty's you'd have to disconnect the wire harness, requiring removing the door panel)