Nico,
you need to forget that it's a BlueTooth device.
The trick with the AirCable is, that it works like
a serial cable to your mobilephone.
The Zaurus will never know, that there's a
BlueTooth connection. All you need to do, is to
setup an IrDa connection profile and add in the
/etc/ppp/peers/IRDAxxxxx file a first line with
"/dev/ttyS0".
That's the way it works.
It's explained at
http://www.trisoft.de/bluetooth.htm.
Unfortunately this page is actually not translated,
but i guess Babelfish will give you a good idea
what it means
///TRIsoft
Marc Stephan