Any further info on this? It doesn't seem to work for me either.
You need to enable the JSP Compilation Support. Righ-click on the project and select Properties. You should see a "JSP Compilation Support" section. Check the box and define the root folder and it's done.
I've got a project that has several different wars, and several different web roots.
Is it possible to extend the IDE to allow multiple webroots within a single project?