De Ajuda do Firefox :
ActiveX is a Microsoft technology that is used to add functionality to Windows programs.
ActiveX "controls" are often used to enable Microsoft's Internet Explorer browser to view and use multimedia content embedded in web pages (for example, Flash applications). They are also used to add new functions to the browser (for example, toolbars).
Firefox does not support ActiveX technology for multiple reasons.
- ActiveX is only available on Windows operating systems, and as a result webpages that require it will not work on Linux or Mac.
- ActiveX integration with the Windows operating system has made it a target for malicious software (Malware).
Então, sua melhor aposta seria usar o IE por meio do Vinho .