I've attached the test software I wrote to connect to a Zigbee-based Brultech (www.brultech.com) ECM-1220 Power monitor via a ConnectPort X2 from another host on the network. What I assume is of primary interest here is that the program polls the ConnectPort X2 Control Port via XML-RPC, finds ECM-1220's assigned TCP port by its Zigbee NodeID, and connects to the device. The code assumes that the desired Zigbee device has already been discovered via the X2's web interface, so I'm just enumerating devices rather than discovering them.
The ECM-1220 just sends our data packets and has no command/rsponse protocol, so there's a lot of code that deals with it's idiosyncracies. On the other hand, the basic ideas of determining a Zigbee device's TCP port should be of interest to others.
I consider the code to be GPL, and will most likely publish it to my Web site (www.beaststwo.org) in the future. I'm not a great programmer, so please forgive my excessive comments and non-elegant code.
Thanks to JordanH for his help and understanding with my dumb questions.