Actually a schematic of the hub can be reverse engineered in 5 minutes.
1. Pixelnet coming out of the ether dongle on the RJ45 is Pins 1 & 2 is PN universe 1, Pins 3 & 4 is PN universe 2, Pins 5 & 6 is PN universe 3, and Pinst 7 & 8 is PN universe 4.
The signals to used by a particular hub is defined by the jumper pairs that then feeds 4 driver chips that feeds pins 1 and 2 of each column of RJ45 output jacks.
Pins 3, 4 and 5 are bound together and carry + power to the SSCs via the output jacks, and 6, 7 & 8 are bound together as the power ground.
If you just wanted to test 1 SSC you could build a cable that used pins 1 and 2 to plug into the etherdongle then a small 12v power supply, even a heavy duty dongle would work and inject the power into the Cat5 cable then plug it into the SSC. You could program the SSC to respond to what ever address within a single Pixelnet universe that you want to experiment with. That takes the hub completely out of the picture until you get your software configured correctly. I use a similar arrangement to test SSCs. I just use an old spare pixelnet dongle to test with.
Hope you are making progress.
Tom