I forgot to take a video/pictures of the conversion and intend to document it next time (considering I have 120 of these keyboards it should be no problem).
A special thanks to several contributors on geekhack.
Soarer was the key to being able to achieve this.
There was a couple of tricks that were required to get it USB compatible over PS/2, and at some point (when I have some free time) I intend to show a simple set by step guide.
Previous posts: