From the PSS Home Page click Settings > Shipworks
Once enabled, please update the "module url" setting within ShipWorks to: https://your_pss.app.powersportsupport.com/ship_works.xml
The Username and Password you enter here will eventually be put into Shipworks.
PSS gives you the ability to Disable Order Prefixing and Postfixing. The notes in PSS should be fairly straightforward regarding what these fields do.