On SDxxx and some Axxx (e.g. A560) cameras there's really just an Auto & P-mode (and all the Scene modes).
On my SD700, Av & Tv modes would radically transform the camera. I tried using Fingalo's set_av, set_tv in various ways to implements a pseudo-Av/Tv mode but the camera ignored me.
On the other hand, EWAVR's build is able to control Tv Bracketing pretty effectively.
Is it possible to implement this feature via script? CHDK code?
I'd be happy to help with coding, but I am not sure which direction is best...
Thanks,
mkmenuts.