Assuming you are referring to the Advanced > Send Zwave Command, it requires the full zwave command data as a hex string and sends it to the device.
If you are comfortable with the risks involved, it looks something like this:
Configuration Command Class: 0x70 (from zwave spec)
Configuration Get Command: 0x05 (from zwave spec)
Command takes 1 byte: The parameter number (from device documentation)
So to get the configuration for parameter 13, the encoded command would be something like: 70050D
The result (per spec) of ConfigurationGet will be a ConfigurationReport sent to the device handler (which may or may not be ignored or logged).
Details on encoding the commands requires an understanding of the zwave spec and knowing the command classes (and command class versions) supported by the device.
The basic z-wave tool is much easier to work with. 
