That build from Danne is about as bleeding edge as you can get. Did you remember to wear gloves and safety goggles before starting your camera?
Seriously, I just downloaded and tried out that build and it took me a few tries but it does work--pretty amazing really.

Settings I used:
Make sure the Canon Movie setting is on 1280x720/60 (very important)
Loaded these modules:
crop_rec
lua
mlv_lite
mlv_snd
sd_uhs
In the LUA menu select these scripts to Autorun:
mv1080p_12bit_iso100_24fps
enable SD overclocking
I also used a SanDisk Extreme Pro 95MB/s card and got continuous recording 1736x936 with audio.
You are really pushing it with the H.264 proxy. That used to be the only way to get the EOSM to record mv1080 video but we were lucky to get a few uncorrupt frames.
Thank you Dfort for all these useful informations ! Very cool if we can get 1736x936 with audio!
Do you get it in cropmode or normal with line skip ?
I'm just starting with EOSM and it was a bit frustrating when you come from 5D3 but this is because I didn't know these hidden tips =)
I need H264 proxy for my workflow and it doesn't matter if I can get only 8...11 losless with EOS-M... I prefer to have a cool preview and offline/online workflow !
Do you put your H264 settings in 0.1x ?
What are the risks to enable sd overcloacking ? I didn't use this option in my last test.
Next month, I go to HK and I'd like to find a viltrox speedbooster EF-M to make some test in cropmode with the 11-22mm!