Lets your custom Drupal module run first or last. Uncomment the unneeded.

hook_module_implements_alter.module

/**
 * Implements hook_module_implements_alter().
 */
function MYMODULE_module_implements_alter(&$implementations, $hook) {

  // run last
  if ($hook == 'MYHOOK') {
    $module = 'MYMODULE';
    $group = $implementations[$module];
    unset($implementations[$module]);
    $implementations[$module] = $group;
  }

  // run first
  if ($hook == 'MYHOOK') {
    $module = 'MYMODULE';
    $group = array($module => $implementations[$module]);
    unset($implementations[$module]);
    $implementations = $group + $implementations;
  }
}