Yes, the rods can be inserted after installation, though it is easier to insert prior to installation.
To insert rods into the Cabidor Classic or Cabidor Deluxe:
Place a rubber grommet onto the rod.
Place one end of the rod into one of the shelf pin holes that penetrate the side of the cabinet. (These holes are on the side of the cabinet that is closest to the hinges of the door.)
Gently flex the rod and slide it into the through hole just far enough to get the opposite end past the front trim. Be careful not to scratch the exterior trim of the cabinet with the end of the rod.
Pull the rod back into the corresponding shelf pin hole on the opposite side of the cabinet.
Slide the grommet down the rod until it is tight against the side of the cabinet that contains the through holes.
To insert rods into the Cabidor Curve, select a retention screw assembly as pictured in the parts collection of the instructions. Place the "T" nut into the side hardware channel with the retention rod loop placed over the screw and behind the flat washer. Using the hex wrench, tighten the screw. Repeat the process on the opposite end of the retention rod.