The ArcGIS extension (XGMapLinkArcGISExtension.dll) is located using COM registration.

If you have multiple installations it can be confusing working out which copy you are actually running.  Looking in the registry at:

HKEY_CLASSES_ROOT\Wow6432Node\CLSID\{EDFA6FE2-C2C5-4BE1-9F12-F1ED37D85EE2}\InprocServer32

will tell you where the file(s) are being run from.

If you want to manually register the dll to a particular location you need to open a cmd window as Administrator and then run:

C:\Windows\Microsoft.NET\Framework\v4.0.30319\regasm.exe /codebase /tlb C:\AMS\CMSI_v2.2.0a\code\XGMapLinkArcgisExtension.dll

C:\Program Files (x86)\Common Files\ArcGIS\bin\ESRIRegasm.exe" /p:Desktop C:\AMS\CMSI_v2.2.0a\code\XGMapLinkArcgisExtension.dll