I have a trackpoint from a thinkpad keyboard with a trackpoint mounting a PTPM754DR microcontroller, what I'm trying to do is to find the usage of various pin on the trackpoint board and connect them to a teensy 2.0 that already controls a keyboard (I'm using this firmware https://github.com/tmk/tmk_keyboard), what I've found on various sites and forums like geekhack are info from other trackpoints with a different pinout, I say so because I've traced at least the mouse buttons and saw the vcc and ground that have bigger traces than the others, how can I find the purpose of other pins? I cannot connect that keyboard back to a laptop.
Here is some images of the trackpoint and what I was able, probably, to trace
According to this post on the geekhack forum:
Notice the boards look identical. Also this other post and another:
That last post has everything you need for using your trackpoint on the TMK firmware too.