You just install the plugin, set it as your motion device, and set the ports and pins. There's nothing else that's any different from using the parallel port, once you setup your network to see it, as described in the manual.
I have a UC300ETH, and have run it with Mach3, and UCCNC. I have the kernel speed at 200Khz, because I'm running servos with high encoder counts.
The Kernel speed is set in the plugin control window.