Depends on your skills, I completely ditched every stitch of the factory system in my truck, but could be done reasonably while retaining the factory stuff. Honestly though if you aren't upgrading the speakers in the rest of the truck all you're going to do is overpower them with a good sub.

I've found that with correct dampening of the floor under the carpet a down firing sub, ported out the front can be extremely effective without going too crazy. Basically this is what JL did with the stealth boxes.

But to your direct question, make a good box that fits for that 10 W3 you have, and use an adapter kit from Best Buy or Crutchfield for your input to the amp.