Default [Q] S4 Google Edition physical key lighting

Installed S4 Google Edition and just wondered if there was any way to change the light duration of the physical 'back' & 'home' keys?

They only seem to illuminate when pressed ATM.

Checked other threads but they only seem to be about adding the Nexus style 'softkeys' or removing the lighting function of the above mentioned keys.

Cheers in advance.