I found this on google:
Writing an ActiveXcrement control with C#[
^]
But over and above the technical hurdles, most people aren't even using IE, and therefore, and activeX control isn't viable unless you REQUIRE users to be using IE. Anyone with half a brain wouldn't allow ActiveX controls to run from the browser, so unless your users are on a corporate intranet that REQUIRES them to use IE, you're implementation will be garbage.