From the KAP Forums Dave Mitchell just released awesome Java apps that assist in installing both Stereo Data Maker and CHDK on Canon cameras. They handle card formatting and installation with a click.
The CDHK package should work without modification for USB triggering.
ASSIST (Automatic Simple SDM Installation and Setup Tool) installs Stereo DataMaker
STICK (Simple Tool for Installing CHDK) installs CHDK
From his descriptions:
"The apps take care of any necessary partitioning or formatting (and do neither if things are already OK). They also know that post-2011 Canon cameras can boot CHDK or SDM from FAT32 cards (and hence don't need two partitions on cards bigger than 4Gb). All this means that once you've dropped the photo the apps know exactly what they have to do.
I intend to add a customisation step at the end of the install process to make things easier for KAP or PAP (e.g. ensuring the CFG file settings make USB triggering work 'out of the box', making a simple intervalometer script the default etc)."