How does the Affiliate Plugin "work"?

How does this plugin work exactly? Does it run off of an online processing account like PayPal/2CheckOut?

or can I use whatever payment processor I want, so when someone signs up as a member (under the affiliate script) it just adds that person to their account? Don't really know how to explain it.

I plan on using CCBill or Epoch as my payment gateway so will this plugin still work? Or do I have to use PayPal as a gateway for it to work?