ページに抜粋を追加する

if ( function_exists('add_post_type_support') ) {
 add_action('init', 'add_page_excerpts');
 function add_page_excerpts()
 {
 add_post_type_support( 'page', 'excerpt' );
 }
}

http://www.wpmayor.com/wordpress-hacks/add-an-excerpt-box-for-pages/(@source)
http://elearn.jp/wpman/function/add_post_type_support.html(@see)