Different weapon animation for prone position?

[-Gews- 1]

Is it possible to have a different weapon holding animation for different character stances?

I am trying to create a weapon. I would like the character to hold it like this when prone:

Image from "The Hurt Locker"

but to hold it "normally" when crouched, kneeling or standing.

Another question, is it also possible to make it only usable when prone, like certain anti-tank weapons may only be used when crouched or standing?