How can I stick chocolate wafer sticks like this:
on a mudcake to get this result:
Coat the outside of the cake with a moderate layer of icing to bind the stick cookies. This is analogous to the mortar behind facade bricks in building a wall.
You could also put a drop of icing underneath the bottom, but that probably is not necessary.
Update: I just noticed in the photo you can actually see some of the icing between the cookies, showing this is exactly how the show case cake in the photo was done.