Just added the two under seat drawers to my son's JSW TDI. As long as you own the correct triple square wrench, this isn't a very difficult installation. Pull the 4 bolts. Tip the seat back. Fit the holder to the bottom of the seat. Insert 4 screws. Push in the drawer. Tip seat back into place. Reinstall the 4 seat bolts.
I bought the parts through my office in Germany but they are available here for more money through the Euro VW parts suppliers. Adds two nice places to hide stuff out of sight. Will post photos later.