From this old knowledge base article . I think this DLL is probably only included in older versions of Office? This piece seemed promising:
As an alternative to having end users install Microsoft Office, you can freely download and install the Microsoft ActiveX Control Pad, which also installs Fm20.dll. For more information, see the following Microsoft Developer Network (MSDN) Web site: http://msdn.microsoft.com/en-us/library/ms968493.aspx
However, since the associated tool is from 1997, you will need to start its configuration in "compatibility mode" by right-clicking on the executable file and selecting "Properties", then clicking on the "Compatibility" tab and selecting "Windows 95" in the "Run" section This program is in compatibility mode for: "Drop-down menu. Then run it as an administrator (this worked for me using Windows 8.1).
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