For the benefit of anyone finding this thread later, I will state here that I have an S100 and the firmware update method of loading CHDK works perfectly.
firmware update is disabled in the autobuild for all S100 firmware versions:
#suppress FI2 since it doesn't work
Just thought I'd leave an update here.
The issue with not being able to do a firmware update for the S100 was discovered to be false. The autobuild has the necessary files now for 1.3.0 and 1.4.0.