Migrating Outlook Web Server

I have been using OWS with exchange 5.5 and have been impressed if not spoiled by it. Recently I moved our primary web server to a different server and now it resides outside of our network. Originally it was on a domain controller and proxy server. The exchange server is now separate from the web server and resides on our internal network. How can I setup OWS on the external web server and have it use the data from our internal exchange server?