The Z-1000, and associated Z-Controller are a strange beast. If your intention is to run only the switches, and nothing else, from the z-1000 brick, it is as simple as making sure the brick is phased with whatever transformer you are using to power the track, then attaching a wire from the common of the other transformer to the common screw terminal on the Z-1000. The hot from the Z-1000 then goes to the power plug on the O22 switches. When this is done you can not use the Z-controller (powered from the same Z-1000) to power track. The reason for this is that the Z-Controller inverts the phase of the transformer to it's outputs. The black post on the controller connected to the common screw is a full output, 20VAC short. Because of the way the controller works, you can't 'phase' the output of the Z-controller with the accessory output of the brick.
I'm unsure which "common" follows as being correctly phased to other transformers with polarized outlet plugs.
In any case, I recommend using only one of the z-1000's two outputs at any time. They don't play well together, and could start a fire if you have a short between them, as there is no circuit protection across the two hots, Ex, from accessory hot to track common through the Z-Controller. At the very least you'll want to put a 8-10 amp fuse on the hot terminal. The built in breaker will trip in most shorts, but the fuse will keep you from setting your layout on fire if you accidentally have an accessory come in contact with the track.
JGL
Edit: for what it's worth, My brick measures 20.5VAC across the plug for the z-controller, and 14.5VAC across the accessory terminals. I expect these would drop slightly under load.
