If you are needing to use the “flash_image” utility program ( perhaps to get ClockworkMod3 on your system? perhaps because you need want to update to CyanogenMod7? ) and you get a “not found” message when you go to run it like this:

$ su
# flash_image
flash_image: not found

Here’s a link where you can get the program : flash_image

Once you download it you can copy it out to your phone via adb as such:

adb push flash_image /system/bin