OK here is bin file with manual gain control,so if anyone here did this before on 5d could help step by step what to do with this file to get it working on 550D ?
http://groups.google.com/group/ml-devel/browse_thread/thread/1192bdeeb58e94d5
http://groups.google.com/group/ml-devel/browse_thread/thread/1192bdeeb58e94d5