Site Exit smat popup need some tweaks

I have a site exit smart popup, that alerts a message before you exit the website. The problem is that i want to show only fancy alert box and want to remove default browser alert as you can see on this URL [login to view URL] Also i want popup to appear when user navigates away to another URL and not to appear when user navigates in current URL or specified URL's to exempt. Need a quick turn around possibly in less than 8 hours(it is not complicated work for people who know what they are doing)