Think I might have found it...haven't tested.... also the reference files I needed were Interop and InteropCommon dll's found in the C:\ObjectARX 2012 folder.
namespace BCInBLock
{
public class BCCInBLock
{
[CommandMethod("BCC:InBlock")]
static public void BCInsertBlock()
{
Document curDoc = Application.DocumentManager.MdiActiveDocument;
AcadDocument curAcadDoc = (AcadDocument)curDoc.AcadDocument;
string strSend = "-insert ELVTAG \n 0,0 1 45 \n ";
curAcadDoc.SendCommand(strSend);
}
}
}