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

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