So I remember using this trick for my Kindle 4NT(grey version):
http://booksprung.com/change-the-fon...out-hacking-it
However, now that I am trying it with my Kindle 4 Black, I am unable to get any font to work. The option tabs for font types under the Change Font Size option section change but my new font will not appear even when selecting 'alt'. Any help would be greatly appreciated.