I was able to get Mono firmware to my EV3 (So Psyched!!!!)
Anders is a genius!
Here is how I did it a little different from the Man.
Using a Mac & Mavericks as my operating system.
1) Pick 512MB or 2GB or 4GB Download to your Desktop
2) Double Click file you downloaded (creates img file)
3) In Terminal window change directories
4) To find what your disk number is for your sd card. ie disk1, disk2
type in terminal window
Unmount sd card
diskutil unmountDisk /dev/disk1
sudo dd if=imagefile_4GB.img of=/dev/rdisk1 bs=1m
Could not figure out gunzip, so went with plan B
I have a 32GB card and it took 15 minutes for this to load. (freaked me out)
Pay attention to file name image_512MB.img ,image_2GB.img, image_4GB.img