In the meanwhile, please, use http://devnet.jetbrains.net/thread/290032
Before You Begin
Currently, IntelliJ IDEA Scala plugin is in beta stage and is being actively developed. Here is the list of what you will need to try it:
As you see, IntelliJ IDEA has automatically specified the Scala compiler library, and added it to the list of module dependencies. If you want to learn more about project configuration, refer to http://devnet.jetbrains.net/thread/290032.
Creating Source Code
Now everything is ready for the first HelloWorld application.