Currently, you will have to hack the plugin to make CataBlog support comments. In the CataBlog plugin folder there is a file labeled CataBlog.class.php inside a directory labeled lib. Line 213 of this file should be updated to this:
$params['supports'] = array('title', 'editor', 'comments');
This will enable comments for the CataBlog custom post type, but I am unsure if this will actually create the comments interface in your site’s theme. You may have to add code to your CataBlog Single’s PHP template file. Good luck and let me know if you are successful at enabling comments. If it is this easy perhaps I will add a checkbox in the options interface to add comments into the supports array. Cheers