Use the latest IntelliJ IDEA release and install the Scala plugin from within the IDE.

Compilation withing IDEA is performed in "-Dlocker.skip=1" mode: the sources are built
directly using the STARR compiler.

The following steps are required to use IntelliJ IDEA on Scala trunk
 - Run "ant init". This will download some JARs from to ./build/deps, which are
   included in IntelliJ's classpath.
 - Run src/intellij/setup.sh
 - Open ./src/intellij/scala.ipr in IntelliJ
 - File, Project Settings, Project, SDK. Create an SDK entry named "1.6" containing the
   Java 1.6 SDK
