1. Boot with Option key held to display the boot menu's firmware password prompt.
2. Press Control-Option-Command-Shift-S to reveal a 33-digit hash (mixed letters and numbers) that contains an identifier for your specific motherboard and the Atmel chip used for your system. In this hash, the first 17 digits are an identifier for the system's motherboard, and the last 16 digits are a hash for the password.
3. Submit the hash to Apple, where someone will put it through a special utility to create a keyfile that is specific for your machine.
4. Place the file on a special USB boot drive and hold Option to load the boot menu and select this drive.
5. The system will read the file and properly reset the firmware password stored in the Atmel chip.