Ok, so I've noticed quite a few people around asking specifically how to install ML who aren't able to do it, and the step that most are missing is actually updating the firmware once the files are on your SD card which is performed as follows. (If you've never updated your camera's firmware, you probably don't know how to install custom firmware, right?)
1) Make sure camera is in Manual mode (M)
2) Go to the third settings menu (Wrench icon w/ 3 dots)
3) Highlight the last line, which lists your firmware version (Should be 1.1.1 currently)
4) Click set, this will bring you to the firmware update screen
5) Click "OK"
6) Magic Lantern will install
7) Restart your camera.
I hope this has helped some folks!