hook_islandora_xml_form_builder_forms()

gistfile1.php

<?php

/**
 * This hook allows modules to add default forms to form builder.
 *
 * @return array
 *   An associative array mapping unique names to associative arrays containing a
 *   single key:
 *   - form_file: A string containing the path to the form definition, relative
 *     to the webserver's document root (such that I might be opened
 */
function hook_islandora_xml_form_builder_forms() {
  return array(
    'Unique Form Name' => array(
      'form_file' => 'full/path/to/form/definition/file.xml',
    ),
  );
}

?>