I would like to include the total number of items purchased as part of the packing slip. This information is included in the shopping cart:

PHP Code:
$totalsDisplay = TEXT_TOTAL_ITEMS . $_SESSION['cart']->count_contents() . $item_separator . TEXT_TOTAL_WEIGHT . $_SESSION['cart']->show_weight() . TEXT_PRODUCT_WEIGHT_UNIT . $item_separator . TEXT_TOTAL_AMOUNT . $currencies->format($_SESSION['cart']->show_total()); 
However that information is dropped for the invoice and packing slip. Can anyone tell me how to get (just the quantity part) to appear in the packing slip?

Thanks