Steps to customize the PO Approval Workflow.

1. Take the seeded workflow (POAPPRV)
2. Right click on the Item TYpe and create a new Item TYpe .
3. Open the Seeded Workflow(POAPPRV) in other window .
4. Copy and paste ATTRIBUTES, NOTIFICATIONs, FUNCTIONS and PROCESSES etc from the the seeded workflow to the Newly named workflow .
5. Verify the workflow
6. Customize the new workflow according to your needs.
7. Save the changes and port it to Oracle.

Login with a PO Super User responsibility, go to Setup -> Document Types, select the PO types for which you want to use the custom workflow, and change workflow fields 'Approval Workflow' and 'Workflow Startup Process' to the new ones.