How to install e-jabbered on a site already running drupal

Hi,
I have a site runnig on Drupal cms and I want to install ejabbered server on it so that when a user logs in to the drupal server he/she also automatically logs in to the e-jabbered server. Can you please provide me with some help as to how and where I should install the e-jabbered server on my site so that it complements drupal.