Buckybase now has per-user search thanks to the wonderful Linked Custom Search Engines.
All it takes is a dynamically generated CSE input file per Buckybase user account.
This file assigns the arbitrary label buckybase_cse to all pages under the glob /manuel/*, and then tells CSE to display only pages with that label (FILTER).
(There are a lot more possibilities, such as boosting or eliminating pages with certain labels, and even assigning synonyms.)
Thanks to Ramanathan V. Guha and the other Googlers behind CSE (yes, that R.V. Guha).