Interesting Ground for a Possible Jailbreak

I found a way to change the contents of the kindle store, and a possible new UYK method. The update may have to be crafted, but I found that by changing the contents of /mnt/us/.active_content_sandbox/store/resource/cachedResources , we can actually get an UYK package to start to sideload, but it will give an error code U007 (invalid signature), followed by U004 (about half of the time, means update missing). Could someone take a look at this?
Also, it's probably pointless unless we get the dev keys on the device using the Kindle store. I was using the 5.6.5 JB as testing in the store, and... it doesn't crash.