There is no support for a single page checkout with Payments Pro, as part of the flow of this type of checkout there must be a page that gathers the billing info, then another page that the user confirms the details and the amount of the order before it will be submitted.
While it is technically possible to implement the individual server behaviors for the checkout to get this effect it is not the way that eCart will create the checkout pages for you.
The biggest problem with excluding a confirmation page is what if the user made a mistake? They would not have a chance to correct it before submitting the order.