I plan to code the same thing your doing...the way Im going to do this is create a button in my admin form...say under a customer detail page. the clickable button will redirect to a php page with only a Universal Email behaviour on it (this will trigger on page load) using the customer ID as a URL reference I pull the required info from the orders/order details records for that customer ID. lay it out nicely (I just simply copied/pasted the code from my confirm.php page) then on the same page it redirects back to the customer detail page :)
Chris