The DD module hard codes the CSS prefix to reference "yui3". However, there is already a ClassNameManager module that handles this for the developer so that the prefix can be created based upon a per
sandbox configuration.
We're running into this issue where the css classnames are not configurable for just this module.
So instead of:

CSS_PREFIX: "yui3-dd",

it should be something like:

CSS_PREFIX: Y.ClassNameManager('dd')

There is also a reference to "yui3-dd-shim" as well that should be changed to something like:

var CSS_SHIM = Y.ClassNameManager('dd', 'shim')