Facebook share button to open in a pop up window

I have difficulty in making the facebook share button to open in a pop up window instead of a new browser tab (target=_blank) in a drupal site with the service links module installed. I want the share to open like the facebook share described in this link: http://www.phpied.com/speed-geeks-guide-to-facebook-buttons/ (the 2nd example at #1: A share link). Which files I need to modify in order to make this work?