Before registering a target you need to know:
The name of the target
The name of the serial device
The path of the layout.xml file generated by mkimage (the path of this file is printed by mkimage when a system image is built)
Now you can register the target by typing:
% chadmin -add-serial-target name/ -device device/ -layout-file layout_file
name is the name of your target, device is the serial device that you have identified, and layout_file is the absolute path of the layout.xml file.
You only need to register a target once as configuration information is saved in your dbg_config.xml file.