osCommerce - bulk add products to cart from external script

[xiao]

I would like to use an osCommerce function in a loop, to add a bunch of products to the cart.

I want to use this function on a page outside of osCommerce (I can include pages).

This is the only thing I got to work:

require('includes/application_top.php');

$ids = array(1,4,18,23);
foreach ($ids as $id){
        $cart->add_cart($id, $cart->get_quantity((int)$id)+1);
}
tep_redirect(tep_href_link('shopping_cart.php'));

But it doesn't work without the redirect at the end.

Is there a way to do this without the redirect?