Look here: LINK. I haven't tried it yet, though.
Absolute must have. I was in the same boat. Upload; see something wrong: make changes: upload: repeat.
The only tool released is the .exe based "Windows" tool, which doesn't mean that it is only usable on windows based systems.
With a program like WineHQ (or wine for short) you can easily use .exe compiled programs on Unix-like systems (this includes Mac OSX since it's based on BSD).
As for the .bat files, well you don't actually need them since they're only scripts containing one line commands.
- unpack.bat contains: packtools --unpack -i x3.fw -o x3
- pack.bat contains: packtools --pack -i x3 -o x3.fw -m x3
On my GNU/Linux based systems, using wine I can easily use FiiO:s "Windows Only™" tool.
The syntax is now:
- for the "Pack" function: wine packtools --pack -i x3 -o x3.fw -m x3
- for the "Unpack" funtion: wine packtools --unpack -i x3.fw -o x3
tl;dr put "wine" in front of the command and you'll be okay.
If you went "wat" when reading this and does not understand it at all, then i can supply you with .sh scripts doing what i just described (which should work on most Unix-like systems using the "bash"(Bourne Again SHell), i.e most modern GNU/Linux distros and OSX).
You'll have to install "WineHQ" on your own firstly though.