I'm searching for the same thing but for the S90. CHDK is not really ready, but I search informations about extra long exposures. Which cameras can get that?
I find that:
( on: http://chdk.wikia.com/wiki/Adding_support_for_a_new_camera
In capt_seq.c we have two modified tasks: capt_seq_task() and exp_drv_task(). These are adapted to support saving RAW files, using a remote (USB) trigger and changing the exposure settings (including the addition of very long exposure times). exp_drv_task() is only required for the optional extra long exposure feature.
Is there something special to do to allow extra exposure shots? Is it only for developpers?
thx for all, for time for everything!!