I'm trying to set up ProSites and came across the problem

I'm trying to set up ProSites and came across the problem of having to set up a different IPN url than I already have in PayPal.

I've been researching this topic in these forums and other forums for another application that also needs an IPN url set into PayPal.

To make sure I understand this right I'd like to layout the process as I understand it and maybe someone can either correct me or confirm this would work:

I only need one IPN forwarding script which will forward the IPN to all the apps, fulfillment services, CRM programs, etc.

Will this script forward the IPN unaltered or will I have to customize it to fit my specific setup?

Thanks!