Google Checkout should be an radio option on Step 2. It functions similar to Check payment. Installing tpl_checkout_confirmation_default.zip will add a Google Checkout button on Step 3 and force customers to go to Google Checkout cart to complete the order.
Your answer allows me to believe that our store Terms would need to be checked off if we have it set up that way.

I asked this earlier because I saw another Zen Cart store and its Google Checkout button was on the Shopping Cart page. This made me assume you could bypass all the Zen checkout steps from 1 -3.

I am more intrigued to start the process.