Hi,
We are using their hosted secure page.
They provided us with the solution for zen cart.
We don't think it was built 100% correctly! It doesn't follow the normal directory structure of the other gateways - they got us to put a script in the root directory. The script they gave us had some errors I spotted also.

I can send it to you if you like and tell you how it was integrated.
Might be a payment gateway the development team could add on in the next release.