Enabling "Soft Power Off" (via the systemui.xml file) and giving it "top priority" (so that it appears at the top of the power-button popup list) was exactly what I needed. It doesn't disable the WiFi, which is fine for me since I kinda like the "Always On" philosophy (as long as it doesn't affect battery life too much, and I don't think it has, in my case), but it turns off the screen and locks the keys immediately. It's not as convenient as the 770 cover, but power-button-enter-button is pretty quick to turn it off, and holding down the power button to turn it back on isn't too horrible.