I'm using AllBest's firmware version 1.00C, as that is what I discovered my camera's firmware to be, it appears there is also a version for cameras with version 1.00B, you can find out by turning on your camera, going to review mode, then pressing Disp, and Funcset simultaneously, and can download version 1.00C here:
http://grandag.nm.ru/hdk/autobuild/allbest-sx100is-100c-51-491.zip Then I copied Fudgeys script to the scripts folder created when you install CHDK onto your card-I used cardtricks- make sure you turn off the lock function, else it won't copy:) Then just go to your settings, by pressing the print, or alt button, selecting the script options, and load the script, change the sensitivity from 10 to 5 or so, 10 should work, but 5 guarantees a good shot. Then exit the menus and Alt mode by pressing the print(or alt) button. Extend the lens by pressing the shutter button, and then press alt again, and hold your camera steady and wait for 1 million volts to flash across the sky! Have fun.