Microsoft® does not support loading 32-bit DLLs or in-process COM servers into a 64-bit application, or vice-versa. So you cannot use 32-bit DLL COM objects in 64-bit MATLAB®.
Limitations of MATLAB COM support are:
MATLAB does not support custom COM interfaces (IUnknown) with 64-bit MATLAB.
MATLAB only supports indexed collections.
COM controls are not printed with figure windows.
MATLAB does not support asynchronous events.
A MATLAB COM ActiveX® control container does not in-place activate controls until they are visible.