Going from pop3 to imap

[tara]

Hi,
I just moved a customer over to our IMAP server (running cyrus) and
there are messages still left on our POP3 server.  I set up a .forward
message so everything relays to the IMAP server.  But, since the
customer's  mail client is now configured for the IMAP server for
incoming and outgoing mail - HOW do I get her old messages over to the
IMAP server?

Thanks
Tara