Can you give a little more detail about the scripts that you are attempting to run with Tableau Desktop and the Oracel EBS Server connection? I am not sure I fully understand the requirements of what you are trying to accomplish.
Is it constantly asking you to sign in each time you are dragging out pills into the view? I would check with the DBA and make sure there is not a setting killing the connection from Tableau Desktop.
I also found this thread that has some additional suggestions for storing the data in a data warehouse then connecting Tableau Desktop to the warehouse.
Hope this helps!