It is as easy as setting up a webcart, adding the products, and adding bitcoin as a payment.

Have you got any idea what webcart script you will use?

here are a few opensource ones

http://www.opencart.com/
http://www.prestashop.com/
http://www.magentocommerce.com/
http://www.cubecart.com/site/home/ < popular
http://www.zen-cart.com/ < also popular