...
(1) Add the lib/emma.jar file to the extension directory of the Java that you are running on your test system. E.G: copy to $JAVA_HOME/jre/lib/ext/emma.jar
(2) Run your Sakai-Demo and run your tests.
(3) Stop the Sakai-Demo. After a few seconds in the Sakai root you should see the file coverage.ec. You now have the raw data to generate reports.
(4) Run emma in report mode. For example:
Assuming that:
html report directory is /home/alan/temp/output/x/tool
Location of source code for your subproject is /home/alan/src/sakai_2-2-006/portal/portal-tool/tool/src/java
Location of your Sakai demo is /home/alan/sakai-demo/
Location of the tool.em from the unpacked output.tar.gz file is /home/alan/temp/output/
...