So. Remember when Shallan tells a truth to those crazy-symbol things, and then goes to a land that seems to be full of spheres? Shallan told the "sphere" (representative of the cognitive aspect) of the goblet to turn into blood. She came back, and voila! The goblet had turned into blood.
However, for more advanced manipulation, I have no idea. Except that it has been said that Hoid is good at it, which means that it could be used for transportation purposes.
I think the basics of power in the Shadesmar (also called the Cognitive Realm) is that beings with intelligence and choices have control over objects in the Shadesmar that have little or no intelligence. Sort of like how things that can move on their own seem to have more "control" or can manipulate things in the Physical Realm.
Everything has a presence in all three Realms (Physical, Cognitive, Spiritual).
EDIT- Notice, most of this is just random musings of my own. Little of it is fact.