Next, disconnect the Kindle DX from the computer. Switch it on, and then navigate to the Kindle Settings menu by selecting Menu > Settings. Within the Settings screen, press Menu again, and select the Update Your Kindle option. Press the five-way controller to begin the update process, and the Kindle DX will pop up a confirmation prompt; press OK, and the update will begin.

Important: The update will now fail, and show a warning to that effect. Don't worry, this is normal; the jailbreak software still worked, and everything is fine. At this point, your Kindle should now reboot itself.

Once the Kindle DX reboots, connect it to your computer again and mount it as a USB storage device. Next, open Kindle-usbnetwork-0.37.N.zip and extract the file called update_usbnetwork_0.37.N_dxg_install.bin. Place update_usbnetwork_0.37.N_dxg_install.bin into the Kindle's root directory, and then repeat the rooting procedure I outlined above to install the USB Networking file on the Kindle.