What exactly would the hwnd of the nicklist get you? There aren't [m]any mIRC commands that operate on hwnds, so accessing hwnds is pretty much a concern for dlls only. If your question is, "how do I get <insert DLL here> to use my nicklist", that sounds like something you should request with the authors of that DLL.
FWIW, a DLL can get the nicklist's window handle by enumerating the parent channel window, so giving it $window(#).hwnd should be enough information to get what you need.
