Adding a rich text editor to Excerpt

I need add to the excerpt field the TinyMCE Advanced editor, any ideas?

I have the qTranslate plugin (multilanguage), and it’s impossible to connect teh excerpt with this plugin and an editor.

Thanks

Just replace the default output. Make sure you unescape the excerpt before you send it to the editor:

add_action( 'add_meta_boxes', array ( 'T5_Richtext_Excerpt', 'switch_boxes' ) );

/**
 * Replaces the default excerpt editor with TinyMCE.
 */
class T5_Richtext_Excerpt
{
    /**
     * Replaces the meta boxes.
     *
     * @return void
     */
    public static function switch_boxes()
    {
        if ( ! post_type_supports( $GLOBALS['post']->post_type, 'excerpt' ) )
        {
            return;
        }

        remove_meta_box(
            'postexcerpt' // ID
        ,   ''            // Screen, empty to support all post types
        ,   'normal'      // Context
        );

        add_meta_box(
            'postexcerpt2'     // Reusing just 'postexcerpt' doesn't work.
        ,   __( 'Excerpt' )    // Title
        ,   array ( __CLASS__, 'show' ) // Display function
        ,   null              // Screen, we use all screens with meta boxes.
        ,   'normal'          // Context
        ,   'core'            // Priority
        );
    }

    /**
     * Output for the meta box.
     *
     * @param  object $post
     * @return void
     */
    public static function show( $post )
    {
    ?>
        <label class="screen-reader-text" for="excerpt"><?php
        _e( 'Excerpt' )
        ?></label>
        <?php
        // We use the default name, 'excerpt', so we don’t have to care about
        // saving, other filters etc.
        wp_editor(
            self::unescape( $post->post_excerpt ),
            'excerpt',
            array (
            'textarea_rows' => 15
        ,   'media_buttons' => FALSE
        ,   'teeny'         => TRUE
        ,   'tinymce'       => TRUE
            )
        );
    }

    /**
     * The excerpt is escaped usually. This breaks the HTML editor.
     *
     * @param  string $str
     * @return string
     */
    public static function unescape( $str )
    {
        return str_replace(
            array ( '&lt;', '&gt;', '&quot;', '&amp;', '&nbsp;', '&amp;nbsp;' )
        ,   array ( '<',    '>',    '"',      '&',     ' ', ' ' )
        ,   $str
        );
    }
}

Save this code in a plugin or in your theme’s functions.php.