Supplier payment method - mass update

My business is switching banks.  We have several hundred suppliers with a payment method tied to an the old bank.  Is there a way to update the suppliers with the new bank payment method?  For example they are set up with Bank 1, payment method ACH1.  We are moving to Bank 2, payment method ACH2.  Without losing the history of the ACH1 payments, is there a utility that will create the the ACH2 methods on the suppliers?  Or has someone done something like this using SQL behind the scenes?

Thanks,

Karin