Outlook Web Access – IP used for website

Our company has one public IP address. We are using it to host our website from our own server. We need to implement Outlook Web Access. We are running Win2000 Server and Exchange2000. Port 80 is automatically directed to the website. Is it possible to redirect OWA to a different port? If so, how is this being done, what port number would we use, and what URL would remote users type into their browsers to access OWA?