1. In Visual Studio's Solution Explorer, add a new ArcGIS command. You should use the Visual Studio .NET IDE integration framework in order to implement a BaseCommand for ArcGlobe and GlobeControl. 
2. Add references to your OpenGL wrapper library and to the ESRI GlobeCore and Analyst3D assemblies. For more information see How To get and install an OpenGL wrapper for .NET.
3. If possible, use the IGlobeHookHelper to allow your command to work in the Engine and ArcGlobe applications.
4. In your class, set a member variable for IGlobeDisplay, IGlobeViewUtil, and ISceneViewer interfaces. In addition, set an array list to store the input coordinates information. See the following:

private IGlobeViewUtil m_globeViewUtil = null;
private IGlobeDisplay m_globeDisplay = null;
private ISceneViewer m_sceneViwer = null;
private ArrayList m_array = null;

5. Declare a structure to store the input coordinate information. See the following:

private struct GLPoint
{
  public string Name;
  public double geoX;
  public double geoY;
  public double geoZ;
  public double glX;
  public double glY;
  public double glZ;
}

6. In the OnCreate method, initialize the ArrayList. See the following:

m_array = new ArrayList(100);

7. In the command OnCreate() method, cache GlobeDisplay, SceneViewer, and GlobeViewUtil and start listening to Globe’s AfterDraw event. See the following:

m_globeViewUtil = m_globeHookHelper.Camera as IGlobeViewUtil;

m_globeDisplay = m_globeHookHelper.GlobeDisplay;
m_sceneViwer = m_globeHookHelper.ActiveViewer;
//Start listening to globe display events.
((IGlobeDisplayEvents_Event)m_globeDisplay).AfterDraw += new
  IGlobeDisplayEvents_AfterDrawEventHandler(OnAfterDraw);

8. In the OnClick event handler, open a dialog box and request the input coordinate from the user. The code below assumes that you are having a windows forms dialog called 'InputCoordinateDlg' which allow to get an input coordinate from the user (Longitude, Latitude and Altitude).  See the following code:

// Open an input dialog box for the user to set the geographical point.       
InputCoordinateDlg dlg = new InputCoordinateDlg();
if (DialogResult.OK != dlg.ShowDialog())
  return ;

9. Get the geographical point from the dialog box and convert it into a geocentric coordinate (OpenGl’s coordinate system). See the following:

// Get the geo coordinate from the form.
GLPoint glPnt = new GLPoint();
glPnt.geoX = dlg.Longitude;
glPnt.geoY = dlg.Latitude;
glPnt.geoZ = dlg.Altitude;

// Convert the geopgraphical coordinate into a geocentric (OpenGL) coordinate system.
m_globeViewUtil.GeographicToGeocentric(glPnt.geoX, glPnt.geoY, glPnt.geoZ, out
  glPnt.glX, out glPnt.glY, out glPnt.glY);

10. Add the new element to the coordinates list. See the following:

m_array.Add(glPnt);

11. Refresh the display. See the following:

// Refresh the display so that the AfterDraw will get called.
m_sceneViwer.Redraw(false);

1. Iterate through the list items.
2. Draw the list items directly on the globe. See the following:

public void OnAfterDraw(ISceneViewer pViewer)
{
  foreach (GLPoint p in m_array)
  {
    GL.glPointSize(10.0f);
    GL.glColor3ub(0, 255, 0);
    GL.glBegin(GL.GL_POINTS);
    GL.glVertex3f((float)p.glX, (float)p.glY, (float)p.glZ);
    GL.glEnd();
  }
}

See Also: