First I recommend you update Java if you have an older version installed; that will block the current malware.
As to detection (and eventual removal) of the trojan's presence in Firefox, I don't know. The Safari instructions look for certain items the trojan installs at certain locations. While you can easily substitute 'Firefox' for 'Safari' in the Terminal command, it's by no means certain (although likely) that the malware-installed items have the same name or are at a comparable location for the response to be meaningful. We'd need confirmation of this one way or the other.
