How to pass NT Domain into Exch 2K URL?

How to I pass UserID:Password AND NT/2000 Domain into http://USERID:PASSWORD@{mail.Server.com}/exchange/USERID

I currently have two domains that are serviced by one email (Exchange 2000) server.

In OWA 5.5 I passed parameters to the Logon.asp How do I do the same function here?