How to attach custom 'Final Payment Register' so that it runs when a Payment batch is confirmed in 1

In 11i, when the payment batch is confirmed and when we mark the checkbox 'Print Final Register' in the 'Payment Batch Actions' window , the standard program 'Final Payment Register' is launched automatically. We now have a requirement to add new fields to the standard Final Payment Register report and so we are creating a custom payment register. Now, how do I make this program run automatically when a payment batch is confirmed (instead of the standard program).
Is there any setup for that ?