Go to the Google Play Store and download an app called the "Nexus Flashlight", it supports a flashlight(torch) application and also has lockscreen support.
Plus! It only works on Nexus devices and I think a few others.
I assume you mean like a lockscreen widget right? If yes, this is your app. Turning it on and off from the lockscreen sometimes has a delay but it's only half a second.
EDIT: And yes! Cyanogenmod supports changing DPI, at least as far as I'm aware. I'm able to do this on my Inspire 4G running Cyanogenmod11. I got a boot loop by messing with this before, so make sure you know what you're doing and make a nandroid backup for safety!