I have a working hacked version of 3.2.4 ecommerce that uses paypal. It is a much simplified system that does not support returns.
I use the OpenACS shopping cart and just send a order total with the order id to paypal.
WOW. I just read that document. They have changed the API a little and actually documented it. When I started a while ago, there was no documentation available.
I will be cleaning up the code this week.
