I think S3Pe currently has a drop-down box in CommonBlock called 'Is Visible In World Builder' instead of UNK7. It's changed a few times! Inge and Peter put a list up on the S3Pe site which has a record of what has been changed. http://dino.drealm.info/den/denforu...php?topic=306.0
It's easy to modify the in-game objects to show up in CAW, but for Riverview some of the objects are in the DCCache files and others (like the bridges and distant terrain) are in the World file. This means that you have to actually clone the whole item to make it show in CAW, otherwise you'd have to get CAW to parse your DCCache files (and the Riverview world file). It works, but I think it's better to clone the items with a modded OBJD, which is what I did, instead of having to set up symbolic links or having duplicates. Also, the game itself will not read Riverview world file unless you are playing Riverview- so it is imperative to clone the bridges and distant terrain, or else they will not show in game for a world other than Riverview.
Please do take a look at my files, I've tested in my game but it would be good to get some other eyes on this, in case I messed anything up (or in case anyone can think of a better way to do this!).