Interspire Mail Service Tweak

Looking for a modification so that customers will only see eligible shipping options depending on the product they are purchasing. If a customer is purchasing an item that not eligible using usps media mail the system should not let them checkout with that shipping option. If it does not show the option or gives them an error stating they can't use that option. Either way is fine. We can work out that once the project gets started. We only need this done for usps media mail. All other products can be shipped using any service but media mail restricts certain products to be shipping using that service so if it is possible to exclude that shipping options when a product is chosen that would be ideal. I am open for ideas on the best and fastest way this can be programmed as well. Software used: Interspire 6.11