if you have a handheld remote that is always the first node in any network. from there if you have a leviton serial controller add that as the 2nd node if possible. then add the other devices any way you want.

the trick with the leviton serial controller as it is a secondary controller not an inclusion controller so you have to copy the network over to it from a main controller. the only 2 main controllers i know of right now are the leviton handheld remote and controlthink thinkessentials software with usb stick. example installation manual here [Link: smarthome.com]

you can test if the network copied over by using the programming guide here

[Link: leviton.com]

which shows the commands to send to the device. then talk to the device through the GC via a free software called Hercules HW (google it). for GC use the tcp client mode and connect to GC on it's private ip address and port 4999 if you are using the first serial port or 5000 if you are using the 2nd serial port (not sure if itach has to. regular gc-100 has 2 serial ports). once hercules says you are connected send a test command to turn on/off one of your lights.

so for example once you are connected via Hercules (software will tell you connected or not) go into the box at the bottom and input
N3,ON < cr > (take spaces out on cr. this website won't let me post it together) just like that (if you want to turn on node 3. if you want node 4 input N4, ON < cr > etc. then hit 'send' button on the right side. you should see the command in the text box above along with if it went through or not.

if everything is successful then the light should turn on. if it doesn't then you need to troubleshoot where the breakdown is occurring.