[Rise]

new_guy, в php:

/* bg0.png, bg1.png, bg2.png */
function metaslider_flex_params($options, $slider_id, $settings) {
	if ($slider_id == 5) {
		$options['before'][] = "$('#подложка').css('background','url(путь/bg'+slider.currentSlide+'.png)');";
	}
	return $options;
}
add_filter('metaslider_flex_slider_parameters', 'metaslider_flex_params', 10, 3);