It's pretty extensive. The two primary ways the author intended this to be used is either interactively, or scripted via batch scripts. I've used both frequently. Don't really know what you might want to accomplish beyond scripting by including invocations from compiled Java code. But take a look at scripting, it might do what you have in mind. Just read on the linked page: "If you want to start the application from within another program (e.g. an Ant script or your own program)...", so the author thought of that, but only by invoking the main class he provides; he doesn't appear to have provided a documented class library that you can access directly.
Hope it helps.