Another update then... good news and bad news. I'll start with the good news: it looks like CHDK for the S5IS (1.01b) is almost done
I can already override shutter speeds and aperture values (and measured a few extreme ones, wow), though ISO override locks the camera, RAW and bracketing aren't working yet, the menu is sluggish in record-mode (is this supposed to be this way?), keys seem to skip most of the time (probably my silly keyboard handling) and lots of minor tweaks still need to be done. I also have to find a couple of other functions in the original firmware and figure out why using the file browser or calendar locks the camera (probably because I didn't find enough functions yet). The OSD functions also appear to work a bit but they are not quite complete yet. All this will, of course, take some time but I guess I can say I'm pretty close to completion, given the work I've done already.
Bad news: I have another set of very important exams coming up and I should actually devote this week to hardcore studying. I guess, heh, this will delay the process a bit.
Semi-bad news: I don't have another camera capable of running CHDK so I'll have to figure out CHDK default behaviour through the manuals and the code. I think this will also slow down things a bit.
Anyway, for now I have a
short movie showing zebra and rgb histo and
a bunch of pictures at fast shutter times so you can enjoy yourselves until it's done.
I probably missed some bits, I have to rush this out because dinner is ready 
