For importing STL files, we use the code mentioned at the end of http://www.opencascade.org/org/forum/thread_9793/?forum=3 .
It creates a MeshVS_Mesh from the STL file.
MeshVS_Mesh is a subclass of AIS_InteractiveObject and therefore can be transformed via its SetTransformation method.
Is it possible to export such a transformed MeshVS_Mesh to STL?
RWStl::WriteAscii (const Handle &aMesh, const OSD_Path &aPath );
can be used to write StlMesh_Mesh objects.
Is it possible to get an StlMesh_Mesh from a MeshVS_Mesh?