Android: How to handle hardware button events when the device is in sleep mode (with root access)

Question

Short about the app: I have a launcher app, it will be embedded in to the custom ROM in the future, so the app will have root access.

I need to handle mechanical hardware button events after the screen is off. I've done some research, but can't find out a valid way to do it.

Is it possible to it by having root access?