Mac OS X で root でログインできるようにする

EM114-48-23-155:~ yohei$ sudo passwd root

WARNING: Improper use of the sudo command could lead to data loss
or the deletion of important system files. Please double-check your
typing when using sudo. Type "man sudo" for more information.

To proceed, enter your password, or type Ctrl-C to abort.

Password:
Changing password for root.
New password:
Retype new password:

http://www.hideshi.jp/macosx/rootpasswd.html