All of this, somekinda exceeded my scripting skills.
I had serious trouble installing the PIL module to my OSX 1.6.7 Python
Here's a easy Workaround:
The Screenshot Shortcut (Alt + Shift + G) works as soon as the bootloading bar disapears. So it did on my Kindle 3(.2) Wifi US.
So i just took a screenshot. It does not contain the Bootloaderbar!