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Once restarted, reopen settings and open the SBT option under the project settings (you can ignore the Scala settings as these defaults are sufficient). Under "SBT launcher JAR file" enter the path to where you downloaded the sbt-launch,jar above and under the VM parameters enter the value specified by the JAVA_OPTS export.
Next you need to configure daffodil to use the version of the Scala compiler downloaded by Ivy. This will be a local setting and not the global FCS setting so each module has to be updated individually. Right-click on daffocil-core and select "Open Module Settings". Then for each module, open up it's children, select "Scala" from the list of children and click the "Use ordinary compiler" for the Compiler Installation. This should default to scala-2.9.1 which is the version downloaded by Ivy and configured in the Intellij project.
Finally, under Under the Edit Configurations menu (drop-down) make sure you have a target. You can create a new target to build all tests by clicking the plus sign and then selecting "JUnit" as the test type. Then in the dialog make sure you select the correct class path (i.e. daffodil-core) and path to the core and then check "Run SBT Action" and in the "..." dialog select "test:products".