Tax - How to apply ITIN for Parents

Hi
My parents came to USA on 7/1/03 and returned 10/15/03.
I've the copies of my parents passport, I-94 (front and back).
Also parents-in-laws are coming to USA on 3rd week of march.


a) Can i apply the ITIN for my parents?
b) Can i apply the ITIN for my parents-in-law before their arrival to USA?

Any help would in this regard will be greatly appreciated.

Thanks in advance...