function UTMToBessel(tmX, tmY)
{
   var coord = m_Map.GetCoordSys();
   var pos = coord.UTMToBessel(tmX, tmY);
   alert(pos.GetLon()+"-"+pos.GetLat());
}

#include "CXCoordSys.h"
#include "CXMapPos.h"

CXMapPos CSampleDlg::UTMToBessel(double tmX, double tmY) 
{
   CXCoordSys coord = m_Map.GetCoordSys();
   CXMapPos pos = coord.UTMToBessel(tmX, tmY);
   return pos;
}