From CHDK FAQ about PoweShot and IXUS:
"Changing the firmware version of a camera requires a firmware update file from Canon. A typical Canon camera will usually be manufactured with several different firmware versions over the life of the model. However, Canon very rarely issues firmware update files unless a serious bug is discovered. What you have on your camera is most likely what you are stuck with."
I know there are firmware dumps for 1.00C, 1.00D and 1.00E, but those are just firmware dumps and not a firmware you should load into the camera.
Why do you want or need th "E" version? I assume you are in the US, and do not see it available at Canon USA. Maybe it is a version not meant for US customers. What if the default language for the "E" version was a foreign language?