How to add rel attribute to menu links created via pages

Hi all,

I'm wondering if it's possible (and how) to add a rel attribute to a page's menu link.
So far I've tried:

  $page->menu = array(
    'type' => 'normal',
    'title' => 'Some totle',
    'name' => 'menu-my-menu',
    'weight' => '-6',
    'options' => array(
      'attributes' => array(
        'rel' => 'shadowbox',
      ),
    ),	

... which is not working.... I'd like to add the attribute to the page's code so as I can export it into a feature for re-use. Hence, editing the link through the menu system with menu_attributes is not an option for me. Neither is including the menu link itself and editing the menu_links.inc in features, for that link will be overridden by the menu link included in the page.

Hope someone has any thoughts on this!

Thanks in advance.