[Dovecot] Cannot authenticate with new Red Hat/Fedora SHA512

RHEL6 and Fedora 14 use an improved password algorithm of SHA512 on a brand new install of the OS (:$6$ in shadow file).

cat /etc/shadow user1:$6$<salt>$<password>:15006:0:99999:7:::

I cannot get dovecot to authenticate. I've search for a way to change the default algorithm in dovecot and found you should use CRYPT but I don't know what to put in the /etc/dovecot/dovecot.conf or /etc/dovecot/conf.d/*

Can this be done or do you need to use an alternate password file with MD5?

Thanks, John.