Creating a payment gateway plugin for ProSites

Hi There,
I have decided to create a plugin that adds an extra payment gateway to prosites. I have no problem with integrating the gateway itself - I can use the existing gateway files as a template, what I can't figure out is how to hook it into prosites itself. i.e. How can I get my plugin to show up as an option in the list of gateways? Is it simply a case of using "psts_register_gateway" in my plugin file?