Custom Requisition Approval

We currently use a supervisory based approval hierarchy for Purchasing.  We have a request from one department to always insert a specific user into the approval process.  Is there a more simple way of doing this other than having to switch to using AME rules and then updating the workflow in WF Builder?  I know the user could just manually change the approval list each time before they submit the req, but it would be nice if there were a saved preference for that or something.  Any suggestions would be helpful.  Thanks.