Or in other words: "How to fire real javascript events". But why? jQuery has already a trigger method for this kind of need ! If you can't get why you have to use this plugin. Try to inject jQuery on this Mootools demo page and run:
jQuery('#v_toggle').click(); //or .trigger('click')
Nothing happens... That's because Mootools & jQuery have their own way to create and fire events. They do this way to support bind namespacing, multiple binding ...

jQuery FireEvent allows you to fire real DOM events. Now, come back to the Mootools page, inject jQuery fireEvent plugin and run:
jQuery('#v_toggle').fireEvent('click');
Even if the v_toggle element was binded with some Mootools magic, because we're firing a real DOM event, all works great ! This plugin is really useful in high conflicted environment where we can't find if an element was binded by one or more javascript libraries.

Fork jQuery FireEvent on GitHub