Custom Approval Workflow : Send E-mail Once Approved

I am in the midst of creating a custom PO workflow from the template that NS now provides.  The reason we want to turn it on is to try and get around the email that is sent to the vendor once the PO gets approved.  Right now when the supervisor approves the PO, it sends out automatically (if the to-be-emailed checkbox is checked), but the sender of the email is the supervisor and not the employee/requisitioner on the PO.  I want the last state in the approval process to send the email to the employee stating that the PO was