I want to use this script in Omega subteheme
Short Answer: themename.info or drupal_add_js().

Long answer: If you always want it to load just use the info file and add a [js] entry. Google can help you there.

Depending on when you'd like that JS to load you might want to define it only when nodes of a certain type are displayed, etc. This changes where you put drupal_add_js() in your template.php. 

If you want it only when you display nodes then stick it in THEMENAME_preprocess_node() and you can use the $vars in there to conditionally load it on a particular node type only, etc