Description of import of various YAHOO libraries into Moodle:

1/ YUI2 version 2.9.0:
* full copy of the "build" directory without any changes
* exact version specified in lib/setup.php

2/ YUI3 version 3.4.1:
* full copy of the "build" directory without any changes
* exact version specified in lib/setup.php

3/ PHPLoader 1.0.0b2:
* removed everything except the lib/meta/* and phploader/loader.php
* updated meta info from git repo at github

Code downloaded from:
http://developer.yahoo.com/yui