Using Post Affiliate Pro (hosted) and Membership

I am trying to use Post Affiliate Pro affiliate software with the Membership plug in.

PAP said that I need to do is add code to each paypal button (http://addons.qualityunit.com/integration-methods/_ipaypalipnother2)
this way paypal can ping the software to generate affiliate commission.

I searched around and found a few topics on the forums but no real solution.

Please help me integrate PAP into WP Membership plug in.

Thanks!

(PS: I understand that WPMU has an Affiliate Plug in but I needed something more robust like PAP)