Autoreciepts for loans invoices - is this possible?

The loans invoices are currently being collected outside of Oracle and the information is interfaced in.  We would like to start doing autoreceipts for this.  My attempt to enter the bank account information for a loans borrower and running the billing, did not default the payment method information into the invoice.  I'm also not seeing anything in loans to specify that this is what I want.  Am I missing something?  I thought that if I create a manual invoice in receivables and the payment method information defaults, that it would in the interfaced invoices as well?
Our iPayment setups do work, so it isn't an issue with that.  It is an issue with getting the payment method information to default when LNS:Billing creates invoices in AR.