Default [Q] Modify the Lockscreen dim delay

I have a GT-I9505 and I'm currently on the Jamal 4.4.2 GE rom.
I have the screen timeout after 15 sec but I'd like to modify the timeout when I'm already on lockscreen.
I'll try to be more clear.

I often power on the display to see (from the lockscreen) if there are some notifications.
In order to let the screen switching off I have to press the power button again or wait an amount of time equal to system screen timeout configured. I'd like to reduce this timeout on lockscreen only e.g. 5sec to have the normal behavior I had on stock TW rom or nexus5 or etc...

I tried to decompile android.policy.jar but I was not able to recognize a variable that could help me.

Are there any suggestions?
Thank you