Simply no. You can change the layout of a track for example Korea where the pit exit could be changed but it is not possible to bring it back into the game. I for 1 wish it could be done then we could bring out mods with cars and tracks but we gotta wait untill someone cracks this code.
I don't know how if it is possible but a starting point to find out is trying out 3DSimEd. You can view the model with that program and possibly convert it to another format.