you would need to hand code the functions to process the transactions through an unsupported gateway. The Gateway should have API documentation that you can use for reference, but this is not something we can offer assistance with.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.