I am curious as to how one might go about creating entites in a map that can be read in as entites in a crystalspace XML file. Very similar to adding entities in a quake map. Are there flags that can be set in blender that designate such objects as a box or a can of soda as objects that can be interacted with, which crystalspace/cel will understand? I am hoping that I can create entites in a map and not have to mess with the world file generated from blend2cs.
I believe blender2crystal has support for CEL entities. Not 100% sure how that works though. I recommend looking at the documentation. Even if you use blend2cs you still don't have to mess with the world file. It is very easy to add an alternative 'entities' file that is loaded together with the world file so you don't have to modify the original world file. The celdemo that you can download from the CS site follows that principle and so does the default level for celtest (check out data/basic_world, basic_entities, and basic_level.xml for a simple example).