Although anyone can use the SDK through the Windows command line, you are most likely to use the command line interface (CLI) if you are developing browser or message content.
If you are developing MIDlets you might use command line options within a Java IDE, for example, to trace MIDlet events.
Configuration options you set on the command line override those you set on Emulator by navigating to Tools > Preferences dialogue box but are not persistent between instances of the SDK. If you need settings to be persistent, use the settings on the Emulator by navigating to Tools > Preferences dialogue box.
For more information on running the SDK from the CLI, see: