Help in passing PIP through the DMZ

I am trying to implement Rosettanet for wM PIP 7B1 in our company. The partner which is going to post the PIP to our IS will post it to a DMZ server and then the IS on that server will forward it to the second server which has the actual Rosettanet and TN installations.
My question is how exactly can I achieve the functionality of routing the incoming PIP to the second server from the DMZ after persisting it on the DMZ, and what would be the steps involved (like using the pub:client:http services etc., saving the file to disk etc). Would I send the PIP receipt acknowledgement from the DMZ server or from the second server. Any detailed infomation or example would be greatly appreciated.