The sensor update package has to be run on a TZT 3 using a USB drive as far as I know. With the USB drive in the connector, go to the Initial Settings menu and then select "Update Network Equipment" and the program will start running. It will identify the network sensors and the versions and the items for which there is new software.
One thing to note that is a quirk of the sensor update software is that you have to create the USB drive using a Windows computer. Even if you use a drive formatted as MS-DOS Fat 32 on a Mac, the updater will not run properly. What's odd is that the TZT 3 unit software updates work just fine when downloaded on a Mac.