I think the wood screws take care of that slight mismatch between the spacing of the Kadee holes and the Atlas holes. You can start the pointed wood screws where you could not do the same as easily for machine screws. Plus they eliminate the tapping step.
I'm going to have to try them.
What I've been doing is tapping one Atlas hole for 2-56 (they come tapped for an odd metric size). I install the Kadee box with a 2-56 machine screw in this hole. Then, on the drill press, I drill through the other hole in the Kadee box and into the frame. Then, I tap that hole for 2-56 and install the second machine screw.
Pete's wood screw method eliminates those steps. Excellent how-to, Pete. Thank you.