Paypal ipn intergration?

[Skulldog]

Since I've seen a few sites here using the code base that also have the Paypal feature, I'm curious if anyone can offer some advice on integrating Paypal ipn into it.

I know i'll be creating a secondary currency in game, that would allow users to buy special pets, but I'm not sure how to go about having the ipn work with adding currency based on how many dollars the user sends.

Perhaps it's easier to just have a 'buy these pet for $2' instead, but once again, I'm not getting too much good info from Google when it comes to customizing the Paypal ipn features. :\