Step 1: Fold down the rear seats. They obscure the trim piece that needs to be replaced, and even then, the large cargo cover won't move into position without doing this.
Step 2: Get the hard part out of the way. The two long trim panels provide the hinge mount for the cover. Take a look at the locations of the fastening tabs on your new trim pieces, and guess the same location on the existing trim piece on the car. Use a small flat-blade screwdriver to pop out the rearward-most bottom tab. Once that one tab is out, the entire trim piece can be pulled and twisted out with some elbow grease. Repeat on the other side.
Step 3: This is the hard part. I don't know how to easily describe in words, other than it takes a lot of prying to get the new piece in. Insert the upper tabs, then one by one use the screwdriver to pry the lower tabs until they pop in. I got a finger bruise doing this.
Step 4: With that out of the way, the rearward grocery bag hangers need to be replaced with resting tabs for the cargo cover. Use large pliers to twist those hangers 90 degrees, and they fall right out.
Step 5: The rearward resting tabs twist right in to replace the old parts.
Step 6: Slide in the cargo cover longitudinally (the seats need to be down), then rotate to its lateral mounting position It clicks into the new hinges very easily. Pop in the liftgate pull-strings (the tabs are already on the liftgate, an obvious sign that FCA didn't want to bear the cost of including the cargo cover for NA cars), and you are done!!
Happy holidays and safe motoring to all.