I slid the hard plastic "cover" over the foam "sensor bracket", placed the sensor in the obvious molded spot in sensor bracket, pressed the cover/bracket assembly onto the ice cube tray so it would make good contact and snapped it into place, and finally ran the sensor wire through it's guides. Works great!
The most time consuming part of the job was removing the freezer contents and then the drawers so I could lean into the compartment and see where everything went. But that was a good excuse to clean everything, and the freezer now looks "good as new".