Affiliate Network Software PPV/PPD

I'm looking for software to setup my own affiliate network, which pays users per download or per view. I've searched many affiliate network software providers but all of them pay out per click, lead, sale.. anyone know how I can pull off paying users for downloads they host on my site? Thanks in advance for suggestions.

I think you can tweak WP E-commerce plugin to do that. It has affiliate feature built-in. I didn't try the affiliate part myself. But I'm sure you'll be able to achieve if you play around with the code.