Thanks. I got as far as this bit...
copy the “mozconfig” file for your platform, from the mozilla/composer/config directory to mozilla/.mozconfig
e.g. for MacOS X:
cp mozilla/composer/config/mozconfig.mac mozilla/.mozconfig
And couldn't find the mozconfig file.
btw, it was the .08 build I was trying.
i5 4440 3.1Ghz, Asus H87M-E motherboard, 8GB DDR3, 2GB DDR5 nVidia card, 2x500GB Seagate hd, Coolermaster 750W PSU running Mint 17.1 MATE and Win7
HP mini, 1.66 Ghz Intel atom processor, 2 GB DDR3, 320 GB hd, Mint 17 MATE