Is there a way to create a link (using an image or text) that will add a certain product to the cart without having to go it's product page?

I have a site that has just one product at the moment and the customer wants it to show up on the main page. I have put the detail on the Category section and set the site so that the category comes up as the main page. They would like to have an add to cart button or link available halfway through the detail so the customer doesn't have to scroll to the bottom of the page to click ADD TO Cart. I have tried to use the ADD TO CART link that the normal ADD TO CART button points to but the shopping cart page turns up empty.

Example of the link that I am trying to use with an image
www.website.com/ index.php?main_page=product_info&sort=20a&action=add_product&products_id=2

Is there a way of doing this?