Oops. I just realized that this is not the right group. chromium-discuss might be more suitable, but I believe this topic is out of scope for any Chromium related group.
I guess you have to use MSDN to explore the APIs Internet Explorer exposes to ActiveX developers and continue from there.Also, Chrome used to have an ActiveX shim back in the day. It was removed more than three years ago, but you can always browse the open source code -