form_load_snip.php

<?php
  //module_load_include('inc', 'user', 'user.pages');
  //$form_id = 'user_register';
  module_load_include('inc', 'node', 'node.pages');
  $form_id = 'group_node_form';

  $form_state = array();
  $args = array($form_id, $form_state);
  // Make sure $form_state is passed around by reference.
  $args[1] = &$form_state;
  $form = call_user_func_array('drupal_retrieve_form', $args);
  $form['#post'] = $form_state['values'];
  drupal_prepare_form($form_id, $form, $form_state);
  dpm($form);
?>