I tried this and I have to say. This finally got my kindle doing what I originally wanted to: that is run anki on it. I did a short video on the results and have to say they are awesome on my kindle 4 nt which you can see here
https://www.youtube.com/watch?v=THuLv2IFLW0 . If anybody is interested I can post changes done. Mainly you need two plugins for anki I made (to allow the 5 button to answer and show answers) and another to change the focus, additionally with a custom config.lua for the kindle 4 NT. Still haven't ironed all the issues yet (undo seems to not work yet), but it's very promising. Thanks a bunch!