Individual Item added to checkout page

Trying to add an individual item to the Checkout page. Added the code below to my copy of the wpsc-shopping_cart_page.php file, which does display the product I want:

echo do_shortcode(‘[wpsc_products product_id=”93121″]’);

The problem is that when you click the Add to Cart button, the standard message below appears. As this is already on the Checkout page, I don’t want it to ask if you wish to go the the checkout page:

You just added “Membership (1 Year Membership)” to your cart.
Go to Checkout Continue Shopping

I attempted to determine if there is a filter that I can use to modify or remove this message. And I can’t find one.

Any suggestions would be appreciated.

The page I need help with: [log in to see the link]