Did this for a mate.
Only 2 files are affected.
Download the mod Direct Bank Deposit from the Free Add Ons section of this site (It is a clone of the money order mod).
Unzip the package and open it. You will see 2 payment mods included, namely dirbankaus and dirbankusa. Choose one of them only (eg dirbankaus) and delete the 2 files relating to the other.
Then rename every instance of dirbankaus to paybyphone (and DIRBANKAUS to PAYBYPHONE), be it a file name or a define or constant within the files. Make any other changes such as messages to the customer, the stuff the customer will see on the site and in the confirmation email.
Upload your files then activate mod in admin and test.
NOTE: We are sorry that Frank is no longer with us.
We are grateful for all his contributions to the Zen Cart community.