Try this:
Make sure you have Internalz Pro Installed on your Touchpad
Once you confirmed it, open the app, go to /var/lib/update, if there are any files copy them to /media/internal.
Now plug your Touchpad to Your PC, Select USB Mode once a warning pops up, go to the Touchpad's USB storage and get the copied update files
The legacy webOS update system was done using .ipk files