You need to implement something yourself as that feature is not available in a c-style CLI.
For example, if you are ok with using the confd_load command and have the user just provide a keypath, you could put something like this in your clispec
<cmd name="show-all">
<info>Show config and oper data</info>
<help>Run confd_load -o -F c -p /your/path/here.</help>
<callback>
<exec>
<osCommand>confd_load</osCommand>
<args>-u $(user) -g $(groups) -o -F c</args>
<options>
<uid>confd</uid>
</options>
</exec>
</callback>
<params>
<param>
<info><path></info>
<help>/path/to/show.</help>
<flag>-p</flag>
</param>
</params>
</cmd>