(This was a question I asked the help desk--they sent me here)
i'd like to enable a subscription service on one of my subdomains--and have pages only available to those who subscribe.I already use paypal and i know i can generate "subscription" buttons that generate ids and passwords, but how do I install their code on my site--so that subscriber access is allowed, and non-subscriber is blocked?

below I've quoted the info paypal provides--could you tell me what would be pertinent and how I would implement it? The areas of major concerns I've prefaced w/ (HOW DO I DO THIS?)--thanks

"Step 1: Enable Password Generation
If you want to use Subscriptions Password Management, you will first need to activate Instant Payment Notification (IPN) from within your Profile.

When you create your subscription button, click the Subscriptions Password Management checkbox.

If you are creating and managing your own usernames and passwords, integration techniques are discussed in the PayPal Subscriptions and Recurring Payments Manual.

Step 2: PayPal generates usernames and passwords
Every subscriber will be given a different randomly generated username/password pair after signing up for your subscription.

Example:

Username: pp-bluekite
Password: dog2sun

Usernames and passwords are stored in both the buyer's and seller's Subscription Details pages.

(HOW DO I DO THIS?)--Step 3: Activate usernames and passwords on your server
The Instant Payment Notification posted to your server will include your new subscriber's username and password.

At this point you have two choices:

1. You can write code on your server to accept the notifications and activate the username/password pair within your system. Learn more.

-OR-

(& HOW DO I DO THIS?) 2. If you are using Basic Authentication with an Apache web server on Linux, you may install and configure PayPal's sample Perl script (premier and business accounts only).

This Perl script will automatically read the IPNs and update your active username/password file.

To begin, your system administrator will have to download the Perl script and follow the installation and configuration instructions.