This works, but requires caution to do! I was trying to get FTP running in El Capitan about a month ago and was thrown off by the font spacing on a website, which inspired me to try "...launchctl load -w /System/Library/LaunchDaemons/ ftp.plist" - with a space between the directory and ftp.plist. This caused errors, because my system saw the / and tried loading all of the launch daemons in that directory. In trying to fix it, I accidentally blacklisted ALL of my launch daemons, rendering my system non-bootable. And it's a hackintosh, which makes fixing things a headache. I was able to fix it by taking some time to learn more about the OS X boot process than I wanted to know, but it took a few days.
Moral of the story: pay close attention, and don't try risky terminal jiggerypokery when you've been up all night and are too tired to think it through clearly.