You will need 2 separate transformers if you wish to power the switches independent of track power.

The first transformer powers the track normally, with the common terminal hooked to the outside rails.

The second transformer gets the common terminal hooked to the outside rails of the track. The power terminal of the second transformer gets connected to the fixed voltage plug on the switches.

If you have a larger transformer with auxiliary output terminals, then use the auxiliary terminals which provide the best operation of the switches. You will only need one transformer then.

The same gauge wire you have to the track can be used to power the switches.

You will now have 2 transformers and 4 wires to power the track and the switches separately.

Larry