How can I restore the "\Seen" state from backup?

[Ciprian Vizitiu]

Hi everybody, 
 
SomeUser deletes SomeFolder by mistake; so I bring
/var/spool/imap/s/user/someuser/SomeFolder content back from tape; I stop
cyrus, I export mailbox.db, I edit it, add back user.someuser.SomeFolder
default lrswpcida, import mailbox.txt, reconstruct -f -r someuser start
cyrus. I can again subsribe to that folder BUT all mails are "brand new";
for some 8000 mails this might not be an option. What am I missing from the
restoration process? Obviously I can not simply restore .../someuser.seen
from tape as in between the deletion of the folder and my restoration from
tape the user has "\Seen" other mails; someuser.seen is skiplist.