Have you tried calling eWay up and asking them if there is any issues with using the current version of this mod with ZenCart v1.5.0?
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I have done some testing and the eWAY gateway does receive the transaction, generates the right response code (the decimal of the transaction) but then the message states "Do Not Honour(Test CVN Gateway)".
It should be an honour statement for a successful transaction. I have not figured out why it fails and eWAY have not been particularly helpful noting that this is not their add-on.
However, eWAY as a gateway provider are very good in the live environment
Folks
For those that use eWAY as a gateway there is now a plugin for Version 1.5.X - see http://www.zen-cart.com/downloads.php?do=file&id=1560