@ a1ex if i can help somehow im in 
Just look up Audionut's signature.
BTW on my 6D when I view (play) the images and when i press the LIGHT button (uppers screen light button) it really displays the histogram and zebras or focus peaking dost on the image.
Yes, that button should be mentioned on the help tab.
But I noticed the histogram is not the RAW histogram, i think it is generated from the preview image..?
It would be nice to be able to see the RAW histo and even the ETTR hint whenever you want for all saved images
Until recently, that required running dcraw on the camera (very very slow); however, some days ago, g3gg0 found out how to use the hardware lossless decoder (which is what we need to decode the CR2). Still, some small things are left to reverse-engineer, such as the file name of the image being reviewed.
Finding these should be straighforward in QEMU. For emulating the 6D (which is something I'd like to do regardless of this particular feature), I need a copy of the the serial flash contents. One can get it with the
sf_dump module (it needs to be updated for 6D and compiled from source). Very easy coding task.