Add post tags support to a custom post type (in this case "portfolio")

gistfile1.php

<?php
/**
 * Adds Post Tag support to a custom post type.
 * 
 * This code is set to work with Arconix Portfolio, however
 * the code should work with any of my plugins, simply
 * change the 1st filter argument to match, i.e.
 * 'arconix_testimonials_defaults' as I structure my
 * defaults pretty much the same across all my plugins
 */
 
 // Place the code below in your theme's functions.php file

function arconix_add_tag_support( $defaults ) {
  $defaults['post_type']['args']['taxonomies'] = array( 'post_tag' );
  
  return $defaults;
}
add_filter( 'arconix_portfolio_defaults', 'arconix_add_tag_support' );