I'll have to look into that.
What I was trying to achieve, is to have the same password for ubiboot ssh console as exists for root user on Harmattan (which is "rootme" as default but I sure hope everybody changes it to something different on their devices...)
The problem here is that as ubiboot runs rootFS from ramdisk, there is no persistent storage and I had an idea of symlinking the existing files from Harmattan.

Now thinking of this, I realise that the correct way to do this is of course by storing the credentials in ubiboot.conf and creating the needed files on-the-fly in init.