Firefox 17 ESR Upload Extension not loading

I have the problem that after upgrading Firefox from Version 10 ESR to Version 17.0.2 ESR the upload extension is not loading.

We are running ZCM Version 11.2.2 (NO monthly updates) in W2k8R2sp1 and Firefox 17.0.2 on Win7x64sp1

Of course I configured extensions.install.requireBuiltInCerts to false

I opened the file "nfileuploadext.xpi" (7-ZIP) and edited "install.rdf" to have a "<em:maxVersion>17.0.2.*</em:maxVersion>"

I checked the Novell Patches but only found a "ZCM File Upload Extension for Firefox 15.0.1 and earlier"

I either receive error message:
"Novell ZENworks File Upload Extension konnnte nicht installiert werden, da es nicht kompatibel ist mit Firefox 17.0.2"

OR when modifying the nfileuploadext.xpi I receive
"Dieses Add-on konnte nicht installiert werden, da es beshädigt zu sein scheint."

Of course I tested several solutions and googled but never got it to work.

Thanks Klaus