Prosites, multiple IPN with Paypal.

Ok, I’m already using paypal else where, and the IPN is already used.

Actually, I need to have multiple pro-sites gateways.

So if for example, I’ve got http://cats.animals.com/pro-sites/ (For all cat lovers to buy blogs) and also

http://dogs.animals.com/pro-sites/ (For all dog lovers to buy blogs) how would I setup more than one IPN?

I was looking at http://codeseekah.com/2012/02/11/how-to-setup-multiple-ipn-receivers-in-paypal/ is that a logical/reasonable way of doing things?