Wordpress custom shortcode editor [BackboneJS & TinyMCE)
There's a great article on creating shortcodes here: http://www.smashingmagazine.com/2012/05/01/wordpress-shortcodes-complete-guide/
Scroll down to the section titled "Shortcode TinyMCE Editor Button" and you'll see an example of what I think you're trying to do.
When we press the shortcode button, a dialog appears that prompts us to type the shortcode parameter