Payone is a german payment system with several product options and clearings. To use Payone you'll need to signup with them first of course. To get started try the (somewhat old) payone demos first. They seam to run on PHP < 5.3 right out of the box.
The library is translated from CakePHP Component. There are new functions created for Bank and PayPal Payments, account validations etc.
https://github.com/mashpie/PayoneComponent All Credits to @mashpie https://github.com/mashpie
Read the documentation provided by Payone carefully and setup the config... test and start with a simple payment.