Start with the selector, carrier, bolt, and recoil spring assembly removed from your rifle. Pull the retainer wire (Shepherd's Crook) from the grooves of the trigger and hammer pins, and remove it from your rifle.

Place the retainer plate such that the open end (Area A) is forward, and slide it along the opposite side of the receiver from where the selector would be positioned. The closed circle and tail of the plate (Area C) will be positioned toward the rear of the rifle, as the selector yoke will ultimately be routed through the closed circle in the retainer plate.

When routing the plate forward, ensure that the open end of the plate is secured in the groove of the hammer pin, between the receiver wall and the hammer spring. It may be necessary to "push" the coils of the hammer spring out of the way in order to seat the hammer pin. Push the plate forward until Area A is securely around the hammer pin and positioned in the groove of the pin.

Once the plate is securely forward, rotate it downward so that the notch at Area B drops around the groove in the trigger pin. Ensure that the plate is routed into the groove in the trigger pin as was done previously on the hammer pin. At this point, if the plate is installed correctly, Areas A & B should be set in the grooves of the hammer and trigger pins, and the hole in the closed end of the plate at Area C should be in line with the hole through which the yoke of the selector is routed in normal installation.

You may now install your selector by routing the yoke through the retainer plate and into it's hole in the receiver wall.

Wasn't that easy?