Modified OSCommerce code

I have an OSCommerce website. For each product listed on the site, I want to have some additional options (similar to the attributes in OSCommerce, but not quite). The reason that I cannot use OSCommerce attributes is that the options are the same for every product, and each option is dependent on what the user has selected for the prior options. To be precise, the products are auto accessories that are matched to the color of the customer's car. So, on the [login to view URL] page I need the user to select the Auto Manufacturer and the Year Manufactured. Based upon that input, the third option will be Color Description. The Color Description is based upon the first two inputs. After the user has selected each of those options they can add the product to their shopping cart. The information must then be retained as part of the order. The price is not variable based on those selections.