I'm building a walk-in closet. What I want to know is how to put a sliding door that slides into the wall? How do you build the wall for the door to slide into? I'm using drywall. I can build the wall with 2 X 4s and put up the drywall but what about the part of the wall that the door slides into, what do you use for support if you don't have a stud to nail it to? HELP please.