As found on the Twitter feed of David Barroso (@lostinsecurity):
DrDuh has a new Github project which is a Mac OSX Yosemite security/privacy guide. There is a brief section on firmware, using Apple’s new Firmware Password feature.
OS X Yosemite Security and Privacy Guide
https://github.com/drduh/OS-X-Yosemite-Security-and-Privacy-Guide