Link To Already Defined Path In Menu Using hook_menu() I'm sure this is an obvious answer but I seem to be missing something important.

How can I add a link to a menu using hook_menu() to an already defined path?  

I'm trying to add a direct link to a node/add page that already exists.

I need to use hook_menu() instead of the control panel.
You can best use hook_menu_alter(), which should be used when "Additional items may be added, or existing items altered."

In custom_node_add.module :

function custom_node_add_menu_alter(&amp;$items) {
  if (aray_key_exists) { //some sanity checking;
    $items['node/add']['page callback'] = 'custom_node_add_page'
  }
}

function custom_node_add_page() {
  return t("Hello World! This is content on my node/add page");
}