Is it possible to instantiate 3D models on a given position by scripting?
Say, I've got a MyModel.fbx file and I want to create lots of instances of this model in a scene each one with a position, a rotation and a scale. What possible ways could I do that? Would it be better to use .NET, COM or NwCreator?
firstly, NwCreate is the correct direction. NwCreate provides two means: either for export of NWD files from a third party application (LiNwcApi) or to implement a file loader (LiNwcLoader) for NavisWorks. So, the second one meets your requirement. It allows you load 3rd file format and convert the data to the models in Navisworks scene. The SDK \api\NwCreate provides samples and API documentation. loader is a good sample.
Secondly, I have to emphasize: NwCreate produces the models in from a blank file, no matter LiNwcApi, LiNwcLoader. That is to say, you cannot create models in the existing file.
A practice is: you could produce the files of your own models with NwCreate, and Append/Merge to the existing file.