FWIW, my panel layout is the standard 7 button Hotrod style layout. I removed the lowest button below/left of the other 6 buttons and installed a TurboTwist2 there for each player.
It does not get in the way of the buttons or joystick. It makes it easy to play Ikari-type, Boot Hill, Tron, etc. I use my thumb on the hand I control the buttons with to roll the edge of the spinner and can still easily control the buttons.
I have not tried DOT yet, but I think it would work for that too. Just set the two right buttons as up/down.
While obviously not the same as the original controls. it does make the games quite playable.
D.