Default [Q] Replacing camera on lockscreen? (Xperia)

I have this Xperia Z with 4.3, which has a feature built into the lockscreen that allows me to quickly start the camera. I have a dislike for the stock sony camera app but when lauching it thu the lockscreen it disregards the pattern lock, etc.

If I remove/freeze the stock camera and try to launch camera from lockscreen, it starts any alternative camera I have installed (doesnt ask me which to start) but it cannot unlock the phone. It asks for the pattern to be entered, only if I just leave the "swipe" lock enabled, it can skip the lockscreen.

Is there a way to replace this default camera app on the lockscreen to work fully, i.e. automatically unlock the phone, but with limited features enabled (no gallery etc).
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