@Inject
public MyPart(MApplication application, EModelService service) {
	List<MPart> parts = service.findElements(application, ID, MPart.class, null);
	if (parts != null && !parts.isEmpty()) {
		MPart myPart = parts.get(0);
		//create the toolbar programmatically
		MToolBar toolbar = MMenuFactory.INSTANCE.createToolBar();
		//create the tool item programmatically
		MDirectToolItem element = MMenuFactory.INSTANCE.createDirectToolItem();
		element.setElementId("myToolItemId");
		element.setIconURI("platform:/plugin/myBundle/icons/someicon.gif");
		element.setContributionURI("bundleclass://myBundle/myBundle.handler.MyTestHandler");
		element.setVisible(true);
		element.setEnabled(true);
			
		toolbar.getChildren().add(element);
			
		myPart.setToolbar(toolbar);
	}
}

@CanExecute
public void canExecute(@Active MPart part) {
//fancy code that checks if this is the part for which the handler should be active
}