The question may seem strange, but I want to make this question clear.
Some talk about the 64-bit components of Active-X 64-bit COM server (ActiveX)
while others argue that the 64x COM implementation is missing http://www.pcreview.co.uk/forums/64-bit-activex-vs-windows-forms-t3764967.html
Who is right? Can I implement a 64-bit Active-X COM server (COM dll)?
64-bit COM is alive and well on a 64-bit version of Windows. If COM were dead, it would not have Windows Explorer. And many, many other components of Windows that depend on COM. There is nothing in x64 code that could interfere with COM.
You can write 64-bit ActiveX controls for IE, but keep in mind that they will only work in 64-bit IE.
Also remember that 32-bit IE is standard for users when it clicks the IE icon, even on 64-bit Windows.