[Dovecot] strip domains

[Netlink Tech]

Hello,
Running FC5 x86_64 with dovecot-1.0-0_8.beta3.rhfc5.at
Using system user/passwds for 99.99% of users...have sql user/pass enabled 
to test virtual users from mysql.

How do I strip off the domain when users provide user at domain.com so that 
my userdb and passdb use just 'user'? (disregarding sql auth...I'm not 
concerned with that right now).

My dovecot.conf auth config:

  passdb pam {
    args = dovecot
   }

   passdb sql {
     args = /etc/dovecot-sql.conf
   }

   userdb passwd {
   }

   userdb sql {
     args = /etc/dovecot-sql.conf
   }

Can I just pass userdb the 'user' using an args= statement? %d?
...and then also to the passdb?

Thanks, Curt