old ibm trackpoint pin scheme
According to this post on the geekhack forum:


  R61 trackpoint pinout (with PTPM754DR) « Reply #20 on: Wed, 23 January 2013, 08:04:09 »
  
  
  DATA
  RST
  BTN1
  BTN2
  BTN3
  CLOCK
  GND
  VCC
  
  
  When connecting to PS/2 interface, DATA and CLK should be pulled up to vcc using 4k7 resistor, RST to GND using 100k resistor and RST to vcc using 2.2uF capacitor.
  
  


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.