by Jim » Fri Jan 13, 2012 8:36 pm
There is a feature called Order API that allows you to write a script that will be executed by the thankyou.cgi after the order has finalized. It might be possible to do something in that script that would allow the shopper to upload a file but I am not aware of how that would be done. Configuration for Order API is found under Merchandising in the backoffice so you can check the help link (? icon) on that page to get more details.