This is a method of loading CHDK manually, using a PS.FIR or PS.FI2 file provided with CHDK. Note that with CHDK this does not actually modify your firmware. It just loads CHDK once. For more information see the FAQ, and the Manual
Start CHDK by "Firm Update" method...
1. Unzip the complete CHDK distribution file to the root of your SD card.
2 Check that there is a PS.FIR or PS.FI2 file in the root directory of the SD card.
3. Start the camera in Playback mode. On cameras with a play button, turn on the camera by pressing play.
4. Press Menu, then press Up once (or scroll down)
5. An option to update the ﬁrmware appears, Select that option. (see Image 1)
6. Conﬁrm the update, (OK - press FUNCT.SET), (see Image 2)