To give a more simpler option to new people, I've uploaded the build I'm using myself.
It has all the modules needed and activated for raw recording.
It also has the settings I'm using (this is the actual build I'm using on my SD card, I removed the rom.bin files in the data section, which will be rewritten with your own camera roms at first startup)
This is just a ML build, including all the needed modules and set up in the way I'm using it, so for use, you camera must have firmware 1.1.6 and already be able to run ML (bootflag enabled).If you haven't already enabled the bootflag, download the nightly build for the 6D on the downloads page and do a firmware update with the 'ML-SETUP.FIR' file which is in the nightly build.
Now here is this all in one, already set up lazy build:
https://drive.google.com/file/d/1_mZQUQrossmi8KgjOFg-HkcuLU7_qz8n/view?usp=sharingWhen using the above build, you will see at that the following modules are enabled:
Out of the box, raw video recording in 1824x1026 - 16:9 aspect ratio in 14 bit lossless MLV format with audio is set.
Now in order to make use of the higher resolutions in crop mode, select a crop mode in the movie tab:
After selecting a crop mode preset, be sure to check the resolution displayed behind RAW VIDEO in the movie tab menu screen.
You can change/set this resolution by entering RAW VIDEO menu (highlight RAW VIDEO on the movie tab screen and press Q button on camera) now you see this menu:
Although instead of N/A there are resolution and aspect ratio displayed.
You can change the resolution by highlighting the option and use the scroll wheel on top of the camera to adjust it by increments of 16 pixels wide.
Now be sure to be in 5x zoom when recording and setting up the resolution.
Once crop_mode and higher resolution is set, you can record in 5x zoom these higher resolutions.
When in 5x zoom, you will get Canon 5x zoom preview, but this is not the actual framing of your recording.
To see the actual framing, you can do half-shutter press on the shutter button (lightly press the shutter button), this enables a preview(although frame rate is rather slow) of your actual recording/framing.
You can use the half shutter button before recording and during recording. Since the actual preview/framing is rather slow in frame rate, I choose to have Canon preview by default and occasionally check framing with half shutter press.
Now with these high resolutions, you will see that you won't get long recording times, since the camera can't write fast enough.
To get some longer recording times, you can enable 12 or 10 bit options in crop_mode submenu.
Go to the ML menu and MOVIE tab, highlight your crop_mode and press Q button:
There is a variety of options here, but most don't work (these options are used on EOS-M), but the most important option is working here, bitdepth.
You can select 8, 9, 10 or 12 bit here. If OFF is selected, you're using plain 14 bit raw option.
10 and 12 bit are really useful, 8 and 9 bit gives posterised shadows, but you can check for yourself
.
For viewing, extracting, post process and convert the MLV files I recommend to use MLV app:
https://www.magiclantern.fm/forum/index.php?topic=20025.0ENJOY
EDIT, this build has the SD_UHS speed hack enabled by default. This works good for SD cards that can handle this speed hack, for example the sanddisk extreme pro 95MB/s series or the newer Sandisk Extreme pro 170MB/s series.
Some cards, which can't handle this hack, can become slower with this hack enabled. Or maybe even won't write at all when the hack is enabled.
When experiencing problems, disable the SD_UHS module in the modules tab (Or buy a better SD card 
): 
