I know this is an old thread, but I think it's still of interest to people...
Is it possible to do this by "shortcutting" E-J and adding my own IPN notification URL on the "Edit Instant Payment Notification (IPN) settings" inside my profile in Paypal?
Or is the IPN URL sent at payment time also used for the refund, and the manual setting above ignored?
This is a real pain for trying to keep records updated.