I got in a legal method, but screwed up....
I have "On - through - Off - On - Back through - Off"
http://www.markhellerelectric.com/tunnelsw.pdf I messed up on "through twice", and there is a way to do it like this by moving the combinations around. But it hurts your brain after a while....
I get enough of that at work!
This is a complicated set of switching for what it is... But there is a way to do it to cover the combo of "On - through - Off - On - Back through - Off" And, "Through Twice"