How do I have two email profiles on the same workstation account?

Here’s my scenario – “User A” logs-in to a workstation. “User B” and “User C” would like to have an Outlook 2003 icon on the Desktop to be able to get their email from the Exchange server while “User A” is logged-in to the Domain. When Outlook is opened, it should prompt for the ID and password for “User B” or “User C” to get their email. It seems like this should be a relatively simple task to accomplish, but I can’t figure it out! What am I missing??? HELP!!!