Thanks for repeating the link, cnd. Here's the relevant part from the interview with Tip McKinny, an old-time musician who recorded about 1928:
--------------
Interviewer: That guitar sounds pretty good on the records. What
tuning did you use?


Tip: We played in what they call 'Italian' tuning, you
know, where they tune 'em up. It was an altogether
different tuning from what I ever done before.
Guitar, fiddle, banjer, everything; all the
instruments were tuned like that. We all tuned 'em up
with the violin.

And the feller that knowed about it, feller by the
name of Sparrow. He knowed how it was tuned up. And
my brother had quite a time tuning the banjo with it.
Some way or other Sparrow showed him how to do that.
And the way we played nearly all of the pieces was in
that Italian tuning.

I used to call it cross-key but they said it wasn't
exactly that. But it would sound out all right. That
man that recorded those records said that was music
like he had never heared. That's what he said.
==============

I have a keyboard next to my computer, and I found a piece by Tip's band (Pope's Arkansas Mountaineers) called 'Birmingham'. It sounds like it's in Eb, but I think they tuned all their strings high and played in the key of D.   

However, I don't see why Tip would say that something so simple was "an altogether different tuning."