Heh... Welcome to the party.
http://www.larian.com/forums/ubbthreads.php?ubb=showflat&Number=509920#Post509920So from what I can gather. When you place a chest, it's SideBar inventory properties will have a random drop loot tied to a chest. These can differ depending on the chest.
So far My question is unanswered and I yet don't know how to place items into chests. All we would need is a library with this type of info or even better is a drop down to select all items. I bet it would have something to do with scripts or something more advanced than I.
As an example for chest "FUR_Chest_A" its inventory will be filled with random vendor junk, as its Inventory is set to RewardSmall;