Email access without network account

We have a few Windows 2000 PC’s set up on the hangar floor for the use of Mechanics, with one generic logon for all of them. Some of these Mechanics have network accounts for the purpose of email. We would like to restrict them to the generic account and have them access email accounts via OWA. Is there a way to create email accounts in Exchange2003 without a network account, that they can access through OWA and be password protected? Or is there a way to restrict access, to a specific PC, to one account? Any help would be greatly appreciated.