Canon have posted english releases of their version 2.4 TWAIN drivers for the Powershot series of cameras (350, 600, A5, A5 Zoom, A50, Pro 70). This release does seem to do some extra processing when importing CCDRAW images.

Download the Powershot 2.4 TWAIN drivers:

English: Win95 / Win98 / WinNT4 (2995KB)