I'm pretty sure you are looking for menu_link_save()
http://api.drupal.org/api/drupal/includes%21menu.inc/function/menu_link_save/7menu_link_save()
as adding the menu_name
in hook_menu()
just puts this callback in that menu instead of defaulting it into the navigation
menu. So, after creating it above, with or without the menu_name
, you should be able to add it to any other menu(s) with menu_link_save()
menu_link_save()
.