Need help in doing headless build in RSA 6.0.1 eclipse 3.0   

I am taking this developer works article to achieve the headless build.
http://www.ibm.com/developerworks/rational/library/08/0722_balaba-liaskovski/. I am successfully achieved all the steps defined in there before "Running the task in headless mode" section. When I try to run the build.xml from runant.bat it able to invoke the ant task but it failed to load the other plugins like com.ibm.xtools.uml.core defined in the Ant task. The difference here is I am using eclipse 3.0 and the author is using eclipse 3.2. Can any one point me why there is difference and what do I do to fix the problem.

I am getting this error.
BUILD FAILED
java.lang.NoClassDefFoundError: com/ibm/xtools/modeler/UMLModeler
at org.apache.tools.ant.Project.executeTarget(Project.java:1223)
at org.eclipse.ant.internal.core.ant.InternalAntRunner.run(InternalAntRunner.java:635)
at org.eclipse.ant.internal.core.ant.InternalAntRunner.run(InternalAntRunner.java:539)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:85)