GNBD multipath with devicemapper?

Hi

I am trying to set up gnbd with multipath.
Accoding to the gnbd_usage.txt file, I understand, that this should work 
with
dm-multipath.
But unfortunatly only the gfs part of the setup is descriped there.

Has anybody experiance with this setup, especially how to set up
multipath with multiple /dev/gnbd* and how to setup the multipath.conf file

Thank you very much

Hansjörg Maurer