caribguy - 6:40 am on Feb 26, 2010 (gmt 0)
Because of Zope's strict separation of code and content, adding a script to a content folder instance is very much discouraged.
I see that Andreas answered your question a long time ago on the Plone mailing list. Paraphrasing that reply: using the ZMI you can add your script to the "custom" portal skin folder, or make it available as a browser view. Browsers views are preferred over portal skins in Zope3.
As a Zope2/CMF user, I'm not very familiar with Plone3 or Zope3 but I hope that other WebmasterWorld members will see my reply and perhaps chime in...