I used these commands:
sudo nvram boot-args="rootless=0"
sudo nvram boot-args="kext-dev-mode=1"
and did a reboot. Then, I flipped the switch on TRIM Enabler, rebooted again, and it worked. System Information shows that my Corsair SSD has TRIM enabled, so I'm assuming all is well.
Yeah, that same process is not working for my mid-2011 11" MBA. I'm fine w/o trim for now but hoping it gets sorted.