My pleasure, i had this all in my mind still when i had my 570IS with the hack. Did tons of reading on it.
If you want to shoot RAW (*.CRW) you need the CHDK hack...just go here
. This is their site...find the one for your camera...load it onto your SD card and you ready to go. This is not a firmware mind you, you will write NOTHING to the camera as all the files are on the memory card.
Like i said, i used it with my A570IS and it was GREAT...live Histograms, DoF calculator, live blinkes and on top, ability to shoot *.CRW. As i said before there is 2 caveat for this all. Since your camera doesnt natively come with raw, you will be writing a unreadable version of a .crw file. This means that you need to get a free program online (look on wiki CHDK site, its listed there) to convert it to a *.DNG file. This will be able to be opened in Photoshop to adjust the white balance and what not. The second issue is, since you will be shooting raw and your camera will not read it, you will need to shot *.CRW and a Jpeg. IIRC my 570IS *.crw file size was approx 15megs, on top of the 3-5meg jpeg. This will fill up your memory card FAST.
PS, you see me use the term RAW and CRW. These are both pretty much the same thing, just different file types. CRW is Canon Raw and RAW is basically just that...i think Nikon has their own version of RAW also. This is just FYI.
Let me know if you need any more info...im packed with useless knowledge hahaha.