The 1st step was to mock up the 12.5" "wedge" to mate the liftout to the existing layout. I screwed in a couple of mending braces to the existing shelving and then a scrap board to support the other end and laid in a piece of wood as the wedge. I then fitted up the new switches and the connecting track between them and it looks pretty close right off the bat.
The North/South straight on the edge of the existing layout had a 30" straight piece of FT in it, so that had to be removed and the O-36 switch and two 10" pieces inserted. The lantern switch stand also had to be relocated to the inboard layout side near the Roadway truck. After mocking it up, it looks like about only 1/3 of the piece of wood will be needed to make up the wedge.
I also installed the new O-36 switch at the top of the existing layout in place of where just a plain O-36 curve was in place. The new switch will allow trains to go straight through across the door and onto the extension rather than just curve around onto the straight on the existing layout. Sounds pretty straightforward, right - not - there was no room for the lantern switch stand on the "right" side of the switch because it would interfere with the existing sidings, so it had to be swapped to the left side. No big deal except for the fact that there is a wall there and no place for the switch stand to go. I ended up having to notch out a small section of the wall for the switch stand to lay into. Had to use a Dremel and cut off wheel cutting into 1" thick knotty pine paneling to create the notch. I'll go back and make it look a little nicer after everything is up and running.
I suspect nothing in this build will be easy. 
