I am trying to import a Gradle project into IntelliJ, and when I get to the Gradle Home
textbox, it is not automatically populated, nor will typing in the path
AFAIK it is GRADLE_HOME not GRADLE_USER_HOME (see gradle installation http://www.gradle.org/installation).
On the other hand I played a bit with Gradle support in Idea 13 Cardea and I think the gradle home is not automatically discover by Idea. If so you can file a issue in youtrack.
Also, if you use gradle 1.6+ you can use the Graldle support for setting the build and wrapper. I think idea automatically discover the wrapper based gradle project.
$ gradle setupBuild --type java-library
$ gradle wrapper
Note: Supported library types: basic, maven, java
Regards