Assuming you are going to have less than 120 LEDs that are similar to the smart strings without the smarts...
Assuming the Ethernet cable coming to your enclosure is coming from a powered hub.
Assuming you are willing to take a chance on an unapproved and untested configuration that might not work.
With the power off, Use a knife to cut through the insulation on the cable going to the passive hub and strip back about 4 inches of insulation while trying to not damage the internal wires. You will cut three of the wire pairs as close to the passive hub as possible - green/green white, blue/blue white, and brown/brown white. Do not cut the orange/orange white pair. Do not untwist the orange pair.
You will need to untwist the other three pairs.
There are three +12 and three ground wires coming from the powered hub as follows:
+12v
White with Blue Stripe
Blue
White with Green Stripe
Ground
Green
White with Brown Stripe
Brown
Strip about a half inch from each wire, twist the three together, and insert into the proper power connection on the passive hub and tighten the screws.
Sometimes the colors in the wires are different, so it is a good idea to test the wires before twisting them together. If one gets crossed, you will blow the fuse. Also, you must observe the maximums, more than 120 rgb leds will most likely burn out the fuse on the powered hub after a few hours of use...