Truckloads of non-node, ancillary data in Drupal + Apache_Solr ???

I'd like to take gobs and gobs of data and dump it onto a filesystem or separtate MySQL DB, but not necessarily import it as nodes in Drupal. However I'd like the ApahceSolr module to pick up on this data, i.e. I'd like my separate Solr installation to have indexed it and made those search results available back through the Drupal search results page.

Does anyone have suggestions as to how I might colocate this data, and/or create new indexes in Solr for Drupal to see?

I'm thinking something in the order of tens of millions of database entries and a few hundred thousand documents in a file system, all indexed by Lucene. So if I search for "Joe Blow" in my Drupal ApacheSolr search box, I can find Joe simultaneously in nodes, external DB's, external files and perhaps even other people's Web content I might have NUTCHed.

Pointers, anyone? Thanks...