Agree, most CCD datasheets are very brief!
You should be able to get something out by toggling the lines as indicated in the datasheet.
There is an integrating period, so you do need to act somewhat quickly hence the need to have
a clock rate in the ballpark of the datasheet recommendation (or have a darkened room/tape it up),
otherwise you'll just get white level. I'm not a CCD expert either, so waiting on your
results and source code ; ) The atmega should be ok-ish to process, but I've no idea if the ADC
in there is fast enough, maybe it is, in the darkened room/taped condition.