Hurdy-gurdys and renaissance fingering

I've been lent a hurdy-gurdy, this is exciting. It's a noisy instrument of French origin (also called vielle à roue) thought to date from 11th C in western Europe or the Middle East.

I've got a very few days access to get as far into hurdy-ness as I can before I have to hand it back so it's hunting for fingering patterns time.

You can't easily use your thumb in fingering, this means that for more than 4 notes in any direction you have to either do a long finger crossing, jump or slide. This is similar-ish to renaissance keyboard music, for which there are fingering treatises based around 4 fingers and no thumb.

So on a brief first scan I have found...

The work of Girolam Diruta, organist (c. 1554 – after 1610)
http://en.wikipedia.org/wiki/Girolamo_Diruta / http://www.newworldencyclopedia.org/entry/Girolamo_Diruta

Claudio Di Veroli (alive now)
http://finger.braybaroque.ie/

Claudio brought a book out in 2008 called Baroque Keyboard Fingering: A Method. In his online introduction there are a couple of clues - that the four finger method makes for better articulation (certainly of Baroque music), that the left hand and right are not symmetrical.#

A brief search for hurdy gurdy fingering has turned up relatively little, the only guide that I've found thus far is that smaller jumps take less time (shock!) so the aim is to plan your fingering around that.

I'm sure there's got to be more stuff than this is to go on, I just haven't found it.

My own experiments lead me to think that the angle at which you hold your hand to the keyboard changes things, that accidentals make a big difference to how easily you can cross fingers, that I'm not interested if I can't find something fairly elegant, which I can't yet. Grr.