[jdt-core-dev] How do I programmatically add an external class folder to

[assaf@xxxxxxxxxxxx (Gina S. Assaf)]

Hi,
    I tried JavaCore.newLibraryEntry(folder, null,null) , it didn't 
work, I guess it only accepts folders that are inside the workspace.
Is there a way to add an external class folder to the classpath 
programmatically. I can do it within the UI (By creating a new folder 
and linking it to the folder in the file system), so I would think it 
would be possible to do it programmatically.
Thanks,
         Gina