[lago]

Completo con lo que faltaba que es poder ejecutar funciones JavaScript y que he encontado por ahi y rula

void __fastcall TForm1::Button1Click(TObject *Sender)
{
 IHTMLDocument2  *doc = NULL;
  IHTMLWindow2 *win;
  if(SUCCEEDED(WebBrowser1->Document->QueryInterface(IID_IHTMLDocument2, (LPVOID*)&doc)))  {
	HRESULT hr = doc->get_parentWindow(&win);
	if (SUCCEEDED(hr))  {
	  BSTR cmd = L"ClearMarkers()";
	  VARIANT v;
	  VariantInit(&v);
	  win->execScript(cmd,NULL,&v);
	  VariantClear(&v);
	  win->Release();
	}
	doc->Release();
  }

Y función con parametros:

void __fastcall TForm1::Button2Click(TObject *Sender)
{
  IHTMLDocument2  *doc = NULL;
  IHTMLWindow2 *win;
  if(SUCCEEDED(WebBrowser1->Document->QueryInterface(IID_IHTMLDocument2, (LPVOID*)&doc)))  {
	HRESULT hr = doc->get_parentWindow(&win);
	if (SUCCEEDED(hr))  {
	  String str = String("GotoLatLng(") + Edit1->Text + "," + Edit2->Text + ")";
	  VARIANT v;
	  VariantInit(&v);
	  win->execScript( str.w_str(), NULL, &v );
	  VariantClear   ( &v );
	  win->Release   ();
	}
	doc->Release();
  }
}