But did you look at this : http://chdk.setepontos.com/index.php?topic=11490.msg112688#msg112688 ?
Yup, that and the thread linked at the bottom should be a good starting point.
* Have your PC issue a command or commands (sequentially or all-at-once) to every camera telling it to start the shooting process.
* When that is complete, and your subject is ready, you will open the red wire (+5) to complete the shot.
I'm not sure what is intended here by "start the shooting process"
If this includes pressing the shoot button, you will need to make sure that multicam isn't trying to poll the camera waiting for the shot to complete. At a minimum this means you need to use mc:cmd() instead of mc:cmdwait(). I'm not sure off the top of my head if other changes will be required.
The default shoot command returns some status in messages. At a minimum, you'd want to flush them after chdkptp is in control again. You can use mc:flushmsgs() to do this. mc:cmd() and mc:cmdwait() automatically do this before sending the command.
Another thing you need to be aware of is when the script is running. When you do mc:start(), it start a script on the camera. The script runs until you send !mc:cmd('exit')
chdk script overrides (setting shutter speed etc) are generally cleared when the script exits, so you must not exit between setting your exposure settings and actually triggering the shot.
On the other hand, chdkptp cli commands (like mdownload) generally expect to be able to run their own script, which will fail if the multicam script is running, so you would need to exit the script before using them. You can use download -nolua while a script to download a single file if you know the exact name.
