Karl, while digging and sifting through databases at my university's library on a film noir project I'm in the middle of I did a bit of searching on Black Mountain. Here is just a bit of what I found.
a book from MIT
a John Cage interview
an essay about the school
General info on the school from the state
some info on Charles Olson
The Charles Olson Research Collection
Expect more later when I have more time.