Default [Q] 2 passwords, 1 for encryption, 1 for lockscreen, possible?

Hi
On my transformer pad I had one password with symbols etc. that I entered when the tablet started and a different easy password with just numbers to unlock the screen quick and easy.
I encrypted my Nexus 4 and if i set the pin to just numbers I will be able to unlock my lockscreen as I wan't but the password when booting is the the same.
If I change the password it will change both the locksckreen password and the boot password to the same again...

Is it possible to use two different passwords? One really hard to guess when booting the phone and one easy for unlocking the screen? And how di I set it up?