Share Outlook2K Calendar on IMAP4 Mail

Dear All,
My company default e-mail account is an IMAP account.
1.Anyway I can share Outlook 2000 Calendar when the default e-mail account is an IMAP account?
2.Can this be done using Exchange server?
3.Is there any 3rd party software that can enable this withuot the use of Exchange server.

T.Q.