title: Extend symfony task in plugin
body: <p>I am working with a plugin in symfony 1.4, and would like to add a listener for a task from another plugin. When the user does <code>php symfony doctrine:build</code> I want my plugin to run a task of its own. Where/how do I register the listener? I did not have any success with <a href="http://www.symfony-project.org/gentle-introduction/1_4/en/17-Extending-Symfony" rel="nofollow">http://www.symfony-project.org/gentle-introduction/1_4/en/17-Extending-Symfony</a></p>
  
  <p>Thank you!</p>