Here is the exact POE schematic I am using for my Omega2.
This assumes that you are using a POE injector. I am converting the POE high voltage to 12v for some relays and then to 3.3v for the Omega2+ and other electronics.
If you are just going to pipe in pure DC to the POE pins of the cable then you won't need all that.
Note the Omega2 can't drive the RJ45 Link and POE status LEDS so I tied the POE led to the 3.3v as a power on indicator.