If you had been keeping an eye on our Developer's Corner subforum you would have spotted the previous discussion about this.
Since you had an EPUB reader on your Kindle, I assume you weren't just using the USE_ALT_FONTS trick, and were jailbroken. In which case, take a look at the jailbreak thread, and the linked hotfix. Depending on how recent your jailbreak was, that might just do the trick.
And if you successfully apply the hotfix, and still want to revert the firmware (get rid of the goodreads integration etc.) you can still do that with some effort, see the general idea here:
http://ixtab.tk/kindle-touch-images/PW2/README.txt
You can get the system image for the old firmware by ripping open an update_*.bin with kindletool.