Import mail accounts from snow leopard

I had a Mac OS X 10.6 server with mailserver enabled.

The system drive went down, but I managed to save most of the data after weeks of work.

However, in the meantime, I had to setup a new mailserver on a Mac OS X 10.7 lion server.

So, now the new mailserver has all new mails, but I need to import the old mails into the new accounts.

OD accounts was exported from OS X 10.6 server and imported to OS X 10.7

How can I import the mail data into the new accounts from my recovered data, without deleting the new mails ?

I don't think the migrate process will work, as the new server is up and running and has a lot of new mails already....

( by the way, there is an error in Apple's documentation for migrating script process.... )