Ok it seem that I can put the 5D2 in to center crop for H264(AVC) (.MOV) and record it just as if I was in FHD(3x3)
These are the reg's to make it work , I set canon menu frame rate to 24 ntsc

I dump the image buffer and this what it cam out
Center_Crop_HD-015.png
Center_Crop_LV-015.pngDNG converted to PNG with dcraw
Center_Crop_1880x1247_RAW-015.pngCenter_Crop_1880x1247_RAW-015.DNGCenter_Crop_1920x1080_MVI_8842.MOVWhy is this important ? First I can put the camera in 1:1 pixel , same as 3x crop_mode but in 3x3 (FHD) for AVC (H264 .MOV) recording not Raw .
This is the first step in getting a bigger res with native canon compression (h264) and hopefully that will help get (M)JPEG (.AVI) working.
Next is how to increase the horizontal & vertical (well mainly horizontal) so we can equal the raw resolutions , for UDH/4k 8bit AVC or (M)JPEG .
Two problem I can see right off the start ,
1st ; change the HD Buffer for increase resolutions (if this can be done , we should have full color realtime preview in extended resolutions as it limited to HD size)
2nd ; the H264/AVC encoder is preset to 1920x1080 in the rom , even thou it resizes the h264 will always be 1080p unless we can get control over it .
This is where (M)JPEG .AVI could save us , there no preset size from what I can see in the rom , so theoretically we should be able to record the extended raw resolutions
which could be great benefit for the low speed write camera's plus we can start to use picture style profiles again like Technicolor Cinestyle but in a 422 color space .
Not sure how all this could be implemented , maybe a custom H264 module or a (M)JPEG Module ?
Maybe a1ex has a idea for that