You should have the source code to read binary DWG files (in different format versions). I don't see open source projects to read fully the DWG format. Most of them are commercial or closed-code. So we have to write our own code, or use the license library to read DWG files.
The codeproject.com has lots of links to help develop ActiveX in COM or .NET. I think you might start to use a library to read all entities in a DWG file first, and then draw them to the canvas (for example System.Drawing.Graphics class using GDI+). The output can be WinForm, WPF, Silverlight or ActiveX depending on your choice. This is lots of work and good luck to you.
-Khoa
