Maybe you could try Tray Touch Toggle from the first post here:
It works the same way as the scripts above (i.e., it enables/disables the HID device) and you can enable/disable Touch by clicking on an icon in the system tray. Just follow the instructions to correctly identify the device. Let me know if you need any help.
This does exactly what I need! Easily installed, and you get a small icon in the tray that toggles touch on and off, and indicates the state by its color. Thanks!
Note that the docs indicate that this application probably doesn't work for non-English systems.
Also thanks to all who have been helpful with the Powershell cmdlets. I hadn't known about any of that before. I'm still curious about how to get them to work, but now it's just to satisfy my own need for learning.