Short answer (no pun intended) flip the plug on one transformer.
Long answer: Why?
When working with two (or more) transformers, the first step is to make sure they are in phase with each other. The easiest way to check this is to take wires from the the common posts on each, and just touch them together. Spark means they are out of phase! Solution is to unplug one transformer, and flip the plug around 180 degrees, then retest. No spark means they are in phase. Mark both plugs with a dot of paint or something so you'll know which way it should go if you ever unplug them.
Now that they are in phase, tie the grounds together. They will always go to the outside rails, and to the one side of accessories, per instructions for each device.
Back to the switches, the 022's will take the ground from the rails. If you don't use the fixed voltage plug, they will take the hot from the center rail. By inserting the plug, you are disconnecting the the center rail connection, and substituting the screw terminal on the plug. Now take a hot wire from your 1033 transformer, that supplies 16 - 18 volts, and connect it to the plug, et voila.
