you would need to add the Authentication For Express checkout behavior to the existing cehckout page.
then build the pp_confirm.php page manually and add the Get payer profile server behavior and the Process Express Checkout server behavior
it would be easier to re run the cehckout wizard using Paypal Pro, make sure to set the names of the pages being created to use unique names, then add a link to the checkout page to click here to use express checkout and point that to the new checkout pages that where created,
this would ensure that the pages created had the behaviors for storing to the database and sending the email in place as well.