I believe that you can get the adapter from Weber. Check out the following link and look at the options. It lists an adapter hose.
http://www.weber.com/bbq/pub/grill/2005/q/gg_reg_q.aspx
By teh way to anyone else looking at a portable BBQ I cannot say enough good things about the Napoleon grills. They are totally made from Stainless Steel so will last forever, which is how long they warranty most of the bits. Seriously check it out;