The Cyrus IMAP daemon can be configured to create mailboxes automagically
if the account was authenticated successfully.
You need to look into default-imapd.conf:
# If nonzero, normal users may create their own IMAP accounts by # creating the mailbox INBOX. The user's quota is set to the value if # it is positive, otherwise the user has unlimited quota.
autocreatequota: 0
Set to "-1" and mailboxes should be created automagically.
In addition the UseSkyrixLoginForImap might be useful for using the OGo password for the IMAP login in the webmailer.