Summary:
You can use the Open Firmware Password application to set up low-level password protection with Mac OS X v10.1 and later.
Apple Open Firmware Update 4.1.7 and later provide the groundwork for password protecting computers at a low level (Open Firmware Password Protection). This feature is off by default. Apple provides the Open Firmware Password utility for use only with Mac OS X v10.1 and later. Apple does not endorse or provide technical support for this feature when used with earlier versions of Mac OS or with any third-party software utilities.
Intel-based Macintosh computers can be protected by firmware passwords as well. The firmware in an Intel-based computer uses Extensible Firmware Interface (EFI) technology—Open Firmware is used in computers that use PowerPC processors.
Warning: Attempts to use firmware in a manner that is not explicitly endorsed by Apple may damage your computer’s logic board. Any repairs that are necessary because of this damage will not be covered under the terms of the Apple One-Year Limited Warranty, AppleCare Protection Plan, or other AppleCare agreement.
Full Story: Apple
