Plugin to Plugin

Provided the other plugin uses a post-type to store it’s content then yes, you just need to find-out the post-type slug to pass into my plugin. The easiest way to do this, if your plugin is doing things in this way, is to go to the add-new page for the plugin’s content and check the browser address-bar. It should read something like:

http://yoursite.example.com/wp-admin/edit.php?post_type=slug-goes-here

Copy the text which appears in-place of my example slug-goes-here (everything after the post_type= and before any & symbols if there are any present). That will give you the post-type name to use in the shortcode:

[a-z-listing post-type="slug-goes-here"]