How about using currency tokens (bills or coins) as a medium for some aspect of The Knowledge?
- Like the 'State' tokens in the Eurozone or US, concise bits of The Knowledge might be directly printed or cast in different runs.
- Information pointing to a repository site (e.g., inscribed stone, a la the Georgia Guidestones).
- Using a document construction scheme (as seen in the movie Contact)* would allow redundant bits to be assembled into a larger whole, potentially carrying more information.
- Mix and match strategies (e.g., Site could provide directions to how to assemble tokens... flip sides pointer/content).
Wide distribution in reasonably durable materials (in the case of bills) would increase chances of survival and (re)discovery.
Perhaps a 'legend' about them, fashioned to travel generations, word to mouth, that would identify them as pieces of a puzzle to be treasured, preserved, gathered, assembled and scrutinized?
Now to soon might be a good moment for governmental participation... I'm seeing more and more awareness and will around the possibility of calamity/collapse in authoritative circles. Maybe we could sell it as a last ditch 'national defense' fall-back? In my (pipe) dreams, maybe it could be adapted as international reserve currency?
* The document assembly scheme from Contact involved patterns at the corners of each page. A document was assembled by matching corner patterns, determining the arrangement of individual pages within the larger document.
In the case of bills or coins, there would be many duplicates of individual pages, increasing the odds that any given page would be discovered and gathered for assembly. Only one is necessary for its inclusion within the assembled document.