incorporating commonwealth bank payment gateway

Your payment gateways are limited regarding Australian users. As a merchant I already have access to a direct gateway and I don't really want to incorporate unnecessary third parties. Ideally, I want to give my customers local options as I am a very local business (ie only serve the immediate area). As such, I'd like to use the commonwealth bank's payment gateway.

Their API is rather simple and well documented. They have various solutions:

Hosted Checkout,
Hosted Session, and
Direct Payment.

Hosted checkout is a basic modal overlay with direct control handed off to the bank. The hosted session is a javascript model where more control is handled locally, but compliance with the bank. And direct payment is a fully documented REST API.

Is it possible to modify one of the existing gateways and make it compliant with the CBA?

It's fully documented on these pages:

https://paymentgateway.commbank.com.au/api/documentation/integrationGuidelines/index.html?locale=en_US

HOSTED CHECKOUT
https://paymentgateway.commbank.com.au/api/documentation/integrationGuidelines/hostedCheckout/integrationModelHostedCheckout.html

DIRECT PAYMENT REST API
https://paymentgateway.commbank.com.au/api/documentation/apiDocumentation/rest-json/version/latest/operation/Transaction%3a%20%20Authorize.html?locale=en_US#url_merchantid

Ideally I'd like your help in implementing this and therefore it could be made available across the board for everyone.

In a pinch, I am prepared to give it a go myself if I am able to receive suitable direction from you guys.

Any support is appreciated