ProSites & setting up ipn notification for paypal

I need to set up paypal with dynamic ipn notification since I use paypal IPN for another payment platform. I viewed your link in the ProSites usage section - https://premium.wpmudev.org/forums/topic/multiples-ipn-dynamically-setting-the-notification-url but the link is from 2011 and things have obviously changed. I am hoping that you have another process as I am not currently able to use paypal without IPN. I know there is a way to do it but I am not a programmer so need a user friendly method or very explicit direction. Thanks for the help.