This feature is not available yet. We are currently working on it right now and it will most likely be available in the next service pack. (You will be able to change the template for each View of the Checkout widget from Widget Templates).
If you have any further questions, feel free to get back to me.
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items