From what I can remember, you would be wasting your time. I know for sure using the default classes will only permanently unlock attachments if you have the weapon already unlocked (I tried with the scorpion and when I was finally able to unlock the weapon itself... there were no attachments unlocked).
Easy way to tell is to go in and look to see where you are at in your camo progress (headshots, double kills, whatever) then go play some games using the standard class weapon. Look back at your progess afterwards and see if the numbers have changed.
I can't say for sure but I don't see why they wouldn't count. It's just all about using the specific weapon.