A similar issue exists for me too. It works if I use gdm3 or lightdm as my
desktop manager, but there are some other issues these window managers pose,
which make them not worth switching to. So, I use xdm. I start xsession using,
ck-launch-session dbus-launch xmonad
But I still get "Not Authorized" errors with udisks. How do others handle this?
How/where are you launching udiskie or whatever? It needs to be within the same ConsoleKit session; the display managers you mentioned arrange for the entire user session to be in a CK session, but if you do it yourself you may need to arrange for your whole .xsession or equivalent to be in a CK session.
$ mv .xsession .xsession-real
$ cat > .xsession
#! /bin/sh
exec ck-launch-session dbus-launch $HOME/.xsession-real
^D
$ chmod +x .xsession .xsession-real
And xmonad and any additional programs are then run from .xsession-real.