Yes, you do have to boot into the Recovery HD to accomplish this. My problem is the security command was not available in my Recovery HD no matter what I tried. So this was the solution (not created by me) that worked for me to disable SIP: Boot into the Recovery HD (holding Command-R after the chime and until the progress bar appears) Launch Terminal from the Utilities Menu. Enter /usr/bin/csrutil disable and let it do it's work. It took maybe a minute for me. Reboot back into your regular El Capitan installation and SIP is off. I now can launch the TotalFinder v1.7.1 beta and it doesn’t crash. There are parts of TF that are not working and the author is unsure whether he will put more time into TF. He will make that decision after Apple releases the gold master of El Capitan so he know what he is up against. The Bartender people have found a way to make Bartender work completely. I will try their fix next. It involves turning off SIP, running their special application after a reboot into the regular El Capitan (makes some modifications to the OS) then re-enabling SIP if you desire. Their modification for Bartender works for now pending the final release of El Capitan whether SIP is on or off. So there are ways around SIP assuming Apple doesn’t block them somehow. I just wish Apple would start a program for developers which registers them with Apple and then Apple gives access to whatever in El Capitan they need so that they can make their programs work with SIP enabled.