mogrenewt AccessViolationException

How do I make mogreNewt debug draw

DebuggerInstance.Init works fine but DebuggerInstance.ShowDebugInformation just causes a AccessViolationException

Probably need to look at your code to see where / how you are using it.

In your initialisation code

_world.DebuggerInstance.Init(sceneMgr);
_world.DebuggerInstance.ShowDebugInformation();

In your render code
_world.DebuggerInstance.ShowDebugInformation(false, false); // ShowDebugInformation(true,false) to display float debug text

if you want to display the text you will need the bluehighway font

That is what I'm already doing.

Is there a warning or error message in the ogre.log file?

Does MogreNewt work without debugging option?
If no, then perhaps a dll file is missing or has a wrong version.
There are binaries of MogreNewt.dll, which still includes the Newton.dll file. (Is this called a static link??).
In other cases binaries are seperated. So there is a MogreNewt.dll file, which additionally needs a Newton.dll file (in the correct version).
Also the MogreNewt.dll file should be compiled to the same Mogre version.
So a good option is to use a "binary bundle", which contains Mogre and MogreNewt. Such a bundle was offered, e.g. by user Cygon here.