samba - Mar 2013 - ssha passwords in samba4

Hi,

I have to bring samba4 as a DC in my setup which currently runs zimbra mail
server, I need to migrate all the users with their passwords to samba4.
I am able to extract the users and their ssha encrypted passwords, But am
unable to set the passwords of these users as ssha.
I really don't want to reset the passwords of all the users. Can anybody
tell if/how i can set the passwords of users as pre-encrypted ssha
passwords.
Note:- i donn't have the magic number for encryption in zimbra.