You wouldn't have to modify any field names. You would have to follow the Google checkout documentation and refer to the eCart fields when necessary for things like price and product name.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.