The learning interaction libraries have been removed from Flash CS4. Apparently, they are now only included in Adobe's eLearning Suite.
However, I have found a workaround. The CS3 libraries are compatible with CS4 so you can take the Learning Interaction Library from one and use them in the other. You'll want to place this Library in the folder C:\Program Files\Adobe\Adobe Flash CS4\en\Configuration\Libraries. Here is a demo.
* It has been reported that this fix only works when using Actionscript 2. I have not had an opportunity to verify that limitation.
Order, Designing Online Learning with Flash, for more details on maximizing learning interactions.