I can retrieve all of the posts from the custom category with this particular call to Wordpress_Query

$q = new WP_Query(array( 'taxonomy' => 'jh-portfolio-category',
                          'term' => 0, 'post_type' => 'jh-portfolio' ));

However, let say inside the jh-portfolio-category taxonomy I've defined some sub-groups, how do you specify If only to possess posts from the specific sub-category? Altering the 'term' property towards the term_id as presented in wordpress_term_taxonomy does not appear to operate. All of the posts within that taxonomy continues to be listed.

I am unsure if this sounds like useful for you. I'd an identical problem where I had been looking to getarticles which were of the custom publish_type and taxonomy.

The title of the publish_type is jh-portfolio. Your taxonomy is known as jh-portfolio-category. You didnt specify the title of the term inside your publish, so allows refer to it as foobar. Your get_posts or query_posts function would seem like this:

  get_posts("post_type=jh-portfolio&jh-portfolio-category=foobar");
query_posts("post_type=jh-portfolio&jh-portfolio-category=foobar");

I am unsure how this could translate to Wordpress_Query, but when I needed to guess, I'd say:

$q = new WP_Query(array( 'jh-portfolio-category' => 'foobar',
                                     'post_type' => 'jh-portfolio' ));