The G9 does not have CHDK remote capture support (filewrite hook) implemented. If you are willing to test, it's possible that someone here may be able to add it, although it may be a while before anyone has time.
Alternative, you could shoot, download and delete. The chdkptp 'shoot' cli command supports this with the -rm and -dl options (use help shoot for details)
The G9 may also support Canon's remote capture API. This is not supported by chdkptp, but may work with other applications such as gphoto2.
I'd be happy to test any functionality that can be added. I understand the time constraint concept.
I will try your suggestion with the cli, see how that works.
I have been using the G9 with Canon's RemoteCapture DC program, it works fine but is limited. I don't know if it used the API you are talking about.
After doing more searching and playing with CHDKPTP, it turns out that I can do a remoteshoot with DNG files, but not JPG files. CHDKPTP reports "ERROR: unsupported format". Seems odd since it will write JPGs to the SD card. I can live with this, but would prefer to download JPGs.
Is there any way to make the Shoot button on the Live tab execute a remote shoot function? Or put the two Remote Shoot buttons on the User tab on the Live tab?