IMD is a mesh in this game
. And you should have a special program to convert it into some other format (and then back if you plan to return it to the game). The station is formed by several so-called "modules" which you put together in 3D-Max or some other program that allows you to work with IMD-meshes. There are some special editors (I know 3 of them) that allow people to put this modules together. At least one of them was discussed at this forum (the German one).
CreateTradeStation() as well as CreateStation() are functions that exist inside the engine not inside the scripts. And, unfortunately, this game is not open-sourse.