The real work comes in defining OnKickIdle(). You need to iterate over each item that might have an OnUpdate handler, set up a CCmdUI instance for that item, and call CCmdUI::DoUpdate().  The OnKickIdle() I have written will update the menu items in each of the first-level dropdown menus (e.g. the "File" menu, the "Edit" menu, etc. from a normal app).  You will need to modify it if you have further levels of submenus.  You will need a similar loop if you want to have OnUpdate handlers for a status bar, toolbar, or specific dialog controls.

LRESULT CTestDlg::OnKickIdle(WPARAM, LPARAM)
{
 CMenu* pMainMenu = GetMenu();
 CCmdUI cmdUI;
 for (UINT n = 0; n < pMainMenu->GetMenuItemCount(); ++n)
 {
  CMenu* pSubMenu = pMainMenu->GetSubMenu(n);
  cmdUI.m_nIndexMax = pSubMenu->GetMenuItemCount();
  for (UINT i = 0; i < cmdUI.m_nIndexMax;++i)
  {
   cmdUI.m_nIndex = i;
   cmdUI.m_nID = pSubMenu->GetMenuItemID(i);
   cmdUI.m_pMenu = pSubMenu;
   cmdUI.DoUpdate(this, FALSE);
  }
 }
 return TRUE;
}