[news.eclipse.newcomer] Automatically install features?

[Tom Dalton <tom.dalton@xxxxxxx>]

Quick question (having just lost my 30-min post to a buggy preview post button I don't feel like making this long)

I want to install the Eclipse Modelling Framework automatically (via the command line) on top of my existing Eclipse 3.5 CDT distribution  from a local site archive (emf-xsd-Update-2.5.0.zip).

When I run

java -cp startup.jar org.eclipse.core.launcher.Main
   -application  org.eclipse.update.core.standaloneUpdate
   -command addSite
   -from emf-xsd-Update-2.5.0.zip 


I get 


Exception in thread "main" java.lang.NoClassDefFoundError: org/eclipse/core/launcher/Main


Help!