That is correct. The width tool is only available in Illustrator CS5 and onward.
To get the same effect, you could use the scissors tool and apply it on the points where the width nodes are joined, as shown in Image 4. I used this process to make the sample image.
The issue is: if you need to make adjustments, you'll have to redo the process if you want everything to be aligned properly.
Hope this helped!