how to configure ni_6602 for quad encoding?

Hello there,

It seems like I can read and write from some I/O ports, so something seems
to be working so far.
Anyway, I want to use the ni_6602 as a quad encoder, but have no idea how to
configure the card to work as suck.
The ni_6602 User manual only explains which modes there is, but not how to
set them up (I believe this is something
that the proprietary drivers do automagically).
   Anyway, the Comedi ni_660x driver description says that the encoders
work.  Nice, but how to use them? :/

Kind regards,
Camino