you can use the JQWicket DialogContainer or DialogBehavior anywhere
you would use a wicket ModalWindow I believe. There is an example in
jqwicket-examples.
If it is just for the look of ModalWindow, that can easily be
customized: http://stackoverflow.com/questions/6440826/how-can-i-customize-a-modal-window-using-wicket-1-5
Kind regards,
Roland