Maybe, maybe not. If you are reasonably proficient in reverse engineering, you may be able to figure it out. AFAIK, no one has modified the frames of in-camera video from CHDK yet.
First task is to find a buffer with the video before it is compressed, if such a thing is accessible to the ARM side of Digic.
If that is found, you may or may not be able to do the correction while keeping up with video frame rates.