The way to add an applet to the panel is to right click and select "Add to panel" At the top you have two buttons for "Add program starter" and "Add special program starter"
Find your program behind one of these and add it. I'm not sure about the result, but you could get a little icon to view the temp. I've done it for the system monitor and that gave me processor activity in a little icon
As I have a localized Cassandra so I'm not quite sure what the buttons are called in english.
Don't fix it if it ain't broken, don't break it if you can't fix it