php script to convert old posts galleries to nextgen

We require a once-off script to be coded and run, that will achieve the following: 1. convert old custom posts gallery type (ac thumbs) to nextgen gallery format (current gallery format for new custom post types) 2. create (add) the necessary galleries in the database and backend of wordpress, so that are manageable 3. remove any trace of old gallery data For future, we'd like to just use nextgen only, so this makes sense to convert the old ones. This should be a simple job for scripting expert.