Hook to wp_enqueue_scripts
with a high priority number. For example:
function load_my_style_wpse_90225() {
wp_register_style( 'mystyle', get_template_directory_uri() .'/path/to/stylesheet.css');
wp_enqueue_style( 'mystyle' );
}
add_action('wp_enqueue_scripts','load_my_style_wpse_90225',1000);
That should reasonably load last in line.
Basically the same answer as here: Wooslider custom css