Mac OS X 10.6: Creating a master password
You can create a master password to allow access to any account protected by FileVault. If users forget their passwords for a FileVault-protected account, you can use the master password to access the account and change the FileVault password. You should create a good, secure password for your master password.
Warning:Don’t forget your master password. If you turn on FileVault and then forget both your login password and your master password, you won’t be able to log in to your account, and your files and settings will be lost forever.
To create a master password:
Choose Apple menu > System Preferences, click Security, and then click FileVault.
If the preferences are locked, click the lock icon, and then type an administrator name and password.
In the master password section, click Set Master Password.
Type the new master password, and then type it again in the Verify box.
Click the Key button to the right of the Master Password field to help you choose a secure password.
Type a hint to help you remember your password.