Question [Q] Remap camera physical button


I search at XDA for a couple of days without success, I would like to trigger the camera app in my Xperia ZL with the physical camera button, I'm using Paranoing rom and when I keep the button pressed the phone just vibrates without open the app. In the stock rom even when the phone was locked holding the camera button the phone opens the camera app. I would be happy to just open the camera holding the button with the phone unlocked. I've took a look inside /system/usr/keylayout/ and /system/usr/keychars/ folders without success...