From what you are saying it looks like you are able to boot into recovery CD. If so - you need to get into terminal and start recovering partitions one by one - starting with the system partition. And you need images from Japanese version - not the whole dump, just images of several partitions (system, data...). The problem - nobody have them, you've seen my posts on the-ebook.org. This is why I suggest people start from backup from the beginning
