There's no need for creating a dev/log socket in the bind9 chroot environment and modifying sysklogd to listen on that too.

bind9 opens /dev/log (the one outside the chroot) before calling chroot(2) => Logging still works over that socket from the chroot environement.
See http://cryptio.net/~ferlatte/blog/2004/10/01/#syslog_and_chroot for more info.

That site also has a nice chroot implementation for bind9 on debian: http://cryptio.net/~ferlatte/blog/config/