In my case each user has a gallery. Gallery is a node. I'd like to hide default "Create content" menu and add custom menu link that links to user gallery.
function custom_menu() {
  $items = array();
  $items['galleries/editgallery'] = array(
    'title' => 'Edit gallery',
  'description' => 'edit gallery',
    'page callback' => 'custom_edit_gallery',
    'access callback' => 'custom_access_editgallery',
  );
  return $items;
}
function custom_edit_gallery (){
  global $user;
  $node = node_load ($user->gallerynid);
  return node_page_view ($node);
}
But it doesn't show local tasks tabs(like "Edit" tab).