OpenDWG (DWGDirectX) Polyline Coordinates

Hi, I have recently recieved access to the openDWG libraries.
I am using the DirectX version of the lib (DWGDirectX).

I want to create a PolyLine (or 3DPolyLine), with a number of
vertices.
There is no problem in creating an array, and inserting points.

The problem is that the only representation of these vertices, that I
may set/get is of type double. This makes it impossible for me to set
any extended data on the vertices.

I looked up Od­Db2d­Polyline::­append­Vertex in the C++ documentation,
and it clearly states: "OdDbObjectId
OdDb2dPolyline::appendVertex(OdDb2dVertex* pVertex)". Now, looking up
OdDb2dVertex, finding that it is derived (among others) from the type
"OdDbObject". The class OdDbObject has a method named setXData(...),
but how do I get an OdDb2Vertex in the DirectX lib?

It seems that the DirectX version of the library is hiding some
information, since the vertices are clearly NOT of type double.

Have I overlooked something? Or is there a way around it (other than
using the C++ libs directly)?

I have tried to load a DWG with extended data on the vertices, and
then saving it again, using DWGDirectX. This reveals that the extended
data is preserved through the DWGDirectX lib.

Any info/help on the subject would be appreciated.

Regards, Kenneth