function my_menu() {
   $menu = add_menu_page( 'Page 1', 'bar', 'something', 'else', 'foo' );
   $submenu = add_submenu_page( 'theme_menu', 'Subpage 1', 'Subpage', 'something', 'else', 'foo' );

   add_action( 'admin_print_styles-' . $menu, 'admin_custom_css' );
   add_action( 'admin_print_styles-' . $submenu, 'admin_custom_css' );

   add_action( 'admin_print_scripts-' . $menu, 'admin_custom_js' );
   add_action( 'admin_print_scripts-' . $submenu, 'admin_custom_js' );
}