to autocreate/auto approve standard purchase order by releasing planned order in the planner workben

Hi All, I'm in the process of testing the feature of autocreating and autoapproving the standard purchase order by releasing the planned orders in the planner workbench.  I have set up the approved supplier list, sourcing rules, and assigning the sourcing rule to the assignment set in purchaing module.  When I release the planned order from the planner workbench, however, I still have to run the autocraete function to convert the requisition to purchase order first and then manually approve the PO.  Can anyone advise if the feature I am trying to test is possible and if so, which step(s)