[msl]

It works fine with Firefox 26, but you need to manually change the "maxVersion" attribute in the install package's configuration.

[JIghtuse]

It works fine with it without any tricks. You must use Nightly builds for this http://5digits.org/nightlies

[msl]

Well, that has changend since I last checked, then. I've been using nightlies for a long time, but it sometimes takes a few days before they update the version requirements.