2 two more examples added
source | link

Firstly, not recoment you do that.

Secondly

lets assume your prefix for admin.php is '_trigger_me_'

  1. Submenu

    <?php
    
    function _clean_url_to_repalce_admin_menu($url, $original_url, $_context){
        if ($url == 'admin.php?page=_trigger_me_'){
            remove_filter('clean_url', '_clean_url_to_repalce_admin_menu', 10);
            //return admin_url('someotherpage.php);
            return 'http://google.com/';
        }
    }
    if (is_admin())
    add_filter('clean_url', '_clean_url_to_repalce_admin_menu', 10, 3);
    
  2. Main Menu

    <?php
    function custom_admin_menu_action_hook(){
        global $menu;
        foreach($menu as $k=>$item){
            if ($item[2] == '_trigger_me_'){
                    $menu[$k][2] = 'http://google.com';
            }
        }
    }
    add_action('admin_menu', 'custom_admin_menu_action_hook', 100);
    

I call both examples as "hacks". Thay posible to do, but better to not do that.

update.

if case if satisfied with redirection =)

<?php
$hook = add_submenu_page($parent, $title, $menu_title, 'manage_option', 'callback');
add_action("load-{$hook}", create_function('','
    header("Location:", admin_url("someurl.php?blahblahblah"));
    exit;
'));

in case if you want to substitute this by taxonomy page (edit-tags.php)

<?php
add_action('admin_menu', 'admin_menu_edit_tags_page');
function admin_menu_edit_tags_page(){
    // please set $YOURPARENTSLUG as parent slug of your menu item (parent of your menu)
    // manage_tags to manage_terms of your taxonomy capability (its visible whan you var_dump($wp_taxonomies[$taxonomyyouwant]));
    add_submenu_page($YOURPARENTSLUG, 'menu', 'title', 'manage_tags',  'edit-tags.php?taxonomy=taxonomy');
}

Firstly, not recoment you do that.

Secondly

lets assume your prefix for admin.php is '_trigger_me_'

  1. Submenu

    <?php
    
    function _clean_url_to_repalce_admin_menu($url, $original_url, $_context){
        if ($url == 'admin.php?page=_trigger_me_'){
            remove_filter('clean_url', '_clean_url_to_repalce_admin_menu', 10);
            //return admin_url('someotherpage.php);
            return 'http://google.com/';
        }
    }
    if (is_admin())
    add_filter('clean_url', '_clean_url_to_repalce_admin_menu', 10, 3);
    
  2. Main Menu

    <?php
    function custom_admin_menu_action_hook(){
        global $menu;
        foreach($menu as $k=>$item){
            if ($item[2] == '_trigger_me_'){
                    $menu[$k][2] = 'http://google.com';
            }
        }
    }
    add_action('admin_menu', 'custom_admin_menu_action_hook', 100);
    

I call both examples as "hacks". Thay posible to do, but better to not do that.

Firstly, not recoment you do that.

Secondly

lets assume your prefix for admin.php is '_trigger_me_'

  1. Submenu

    <?php
    
    function _clean_url_to_repalce_admin_menu($url, $original_url, $_context){
        if ($url == 'admin.php?page=_trigger_me_'){
            remove_filter('clean_url', '_clean_url_to_repalce_admin_menu', 10);
            //return admin_url('someotherpage.php);
            return 'http://google.com/';
        }
    }
    if (is_admin())
    add_filter('clean_url', '_clean_url_to_repalce_admin_menu', 10, 3);
    
  2. Main Menu

    <?php
    function custom_admin_menu_action_hook(){
        global $menu;
        foreach($menu as $k=>$item){
            if ($item[2] == '_trigger_me_'){
                    $menu[$k][2] = 'http://google.com';
            }
        }
    }
    add_action('admin_menu', 'custom_admin_menu_action_hook', 100);
    

I call both examples as "hacks". Thay posible to do, but better to not do that.

update.

if case if satisfied with redirection =)

<?php
$hook = add_submenu_page($parent, $title, $menu_title, 'manage_option', 'callback');
add_action("load-{$hook}", create_function('','
    header("Location:", admin_url("someurl.php?blahblahblah"));
    exit;
'));

in case if you want to substitute this by taxonomy page (edit-tags.php)

<?php
add_action('admin_menu', 'admin_menu_edit_tags_page');
function admin_menu_edit_tags_page(){
    // please set $YOURPARENTSLUG as parent slug of your menu item (parent of your menu)
    // manage_tags to manage_terms of your taxonomy capability (its visible whan you var_dump($wp_taxonomies[$taxonomyyouwant]));
    add_submenu_page($YOURPARENTSLUG, 'menu', 'title', 'manage_tags',  'edit-tags.php?taxonomy=taxonomy');
}
1
source | link

Firstly, not recoment you do that.

Secondly

lets assume your prefix for admin.php is '_trigger_me_'

  1. Submenu

    <?php
    
    function _clean_url_to_repalce_admin_menu($url, $original_url, $_context){
        if ($url == 'admin.php?page=_trigger_me_'){
            remove_filter('clean_url', '_clean_url_to_repalce_admin_menu', 10);
            //return admin_url('someotherpage.php);
            return 'http://google.com/';
        }
    }
    if (is_admin())
    add_filter('clean_url', '_clean_url_to_repalce_admin_menu', 10, 3);
    
  2. Main Menu

    <?php
    function custom_admin_menu_action_hook(){
        global $menu;
        foreach($menu as $k=>$item){
            if ($item[2] == '_trigger_me_'){
                    $menu[$k][2] = 'http://google.com';
            }
        }
    }
    add_action('admin_menu', 'custom_admin_menu_action_hook', 100);
    

I call both examples as "hacks". Thay posible to do, but better to not do that.