AtlAxCreateDialog
Visual Studio 2010
Creates a modeless dialog box from a dialog template provided by the user.
ATLAPI_(HWND) AtlAxCreateDialog( HINSTANCE hInstance, LPCWSTR lpTemplateName, HWND hWndParent, DLGPROC lpDialogProc, LPARAM dwInitParam );
The resulting dialog box can contain ActiveX controls.
See CreateDialog and CreateDialogParam in the Windows SDK.