Bind action to hardware key combination

I know that long-pressing power + volume down hardware buttons for a second or so on any screen takes a screenshot - I was hoping to bind an action to the power + volume up combination (specifically I was hoping to make it take a photo without having to open the camera app).

I've looked at a few apps that I thought might do it but they all seem to only allow for remapping of individual hardware buttons/long-presses of individual buttons, not assigning an action to a hardware key combination like this.

I'm currently using cyanogenmod 11 with xposed installed, so an answer requiring either or both would work (although I didn't see any options in cyanogen or modules in xposed that would do this).