PayPal Allowed through CP-$50

[tomdchi]

I currently have this setup where the cp is a signup page from which they add a service plan to a shopping cart.  From there users finish the signup process and are preseneted with a invoice from which they can pay via paypal clicking no a link on the invoice.  I have the cp set up with the ip's of my site to let all of the above work now except the user getting to paypal.
I have all of paypals ip addresses and added them to the allow ip section.  This will not work.  I need to be able to pass paypal's url through the cp and it be resolved.

Essentially this is a walled garden and I know it can be done since there are others out there that have walled gardens.  (sputnik)  They don't have the traffic shapping abilities though.

Would like to get this done asap.

I am thinking that there are others that would need this as well.  Anyone else want to get in on this to make it a full walled garden function?

Tom