I'm not sure if a purchase of COD4 FW3 would give you access to all the other FW3 hacks. Otherwise Heli0s wouldn't give you the option of which game to buy hacks for.
EDIT: My crappy comprehension skillz starting to show. I just reread what you said and I thought you meant to buy the hacks. (not the games)
Then yes, you can use those hacks as long as you have your COD4 sub.