Paypal integration for download access use Phpnuke

I am building a content management portal using PHP-nuke (see [[login to view URL]][1]). I need a Paypal integration when user sign-up to be a member. What I need to protect is the Download and weblink Section, each download entry if user is registered & paid member, he will be able to see the link to the files for downloading. If user is not registered, the link will point to the new user registration form. So the step is: 1. user fill out registration form, 2. go to paypal to pay. 3. IPN return "valid", it will flag on the user table. 4. check if user is valid and logged in. If yes, the file links point to the files to download. If no, the file link point to registration form. You may want to look into PHP-nuke, a very good and fee script, many sites use it. If you have experience with it, that is be nice. there is a free scripts I found on the net called "PHPpal" from <[login to view URL]> which seems something I need, I tried to install it, but spent many hours on it, still couldn't get it work. Need expert help. ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Installation package that will install the software (in ready-to-run condition) on the platform(s) specified in this bid request. 3) Complete ownership and distribution copyrights to all work purchased. ## Platform internet