OK - figured it out, posting here for others that may need in the future....
- The reason the assembly won't come it is because there are two capture "tabs" next to the hold down posts (screws). One of those tabs has to be pressed in the direction of the light bulb to get it to release and allow the assembly to slip out. I would guess this allowed the factory to press the light assembly into the access hole (and stay there) and then later the hold down nuts could be threaded onto the screw posts.
- On the bottom of the lens assembly are two tabs which hold the back half of the lens to the front half. Gently pry up on the each of the tabs with a screw driver and the two pieces will separate. You won't be able to fully get the back half disconnected from the front half -- the 2 pieces are hinged together up at the top, but the hindge joint allows the 2 pieces to separate a bit.
- Once you have them partially separated, look at the area near the screw posts (either right or left side, just pick one - doesn't matter). You will see a tab which can be pressed with a screwdriver blade. This tab is physically part of the front half of the lens assembly. Press that tab towards the bulb and the whole 3rd brake light housing will come out of the hatch access hole. REPEAT -- You can only do this procedure if the front and rear half of the lens have been partially separated....
