How to modify the behaviour of Workflow Action to show modal box when clicked?

Hi everyone, I am trying to modify the behaviour of my custom workflow action, I would like it to show a modal box for some user input before sending it to an url. I've seen similar behaviour in Enterprise Security under the Incident Review page. When user click 'Add Event to Investigation' action, it shows a modal box first. May I know how could I achieve the same behaviour? Thank you p/s. I have created a Modal Box View following this link [link text][1] [1]: https://www.hurricanelabs.com/blog/splunk-custom-modal-view-creation-part-1