I read quite a bit in order to get this right. First I needed to understand how a RAMPS 1.4 board is typically connected - that information can be found here.

Next I needed to map the connectors in the mightyboard (My bot uses Rev-H):

• Bottom Left - LED strip, this one is not used for no so I haven't mapped it
• Above that - Steppers connector, it looks like this:
  
  |———/\————|
  | 2 1 N 2 1 N 2 1 | A
  | 2 1 N 2 1 N 2 1 | B
  |———--————|
  Where 2/1 is coil number and A/B is wire of the coil per RAMPS 1.4 convention.
  The order of stepper motors (from left to right) is X,Y,X
• Bottom middle - LCD screen, not used since I use Reprapdiscount LCD controller
  
• Above that - endstops connectors, the Replicator 2 has only min endstops, the pins are:
  
  |———/\—————|
  | S G S G N S G |
  | G V G V N G V |
  |———--—————|
  Where S is Signal, G is Ground, V is VCC
  Endstops from left to right:
  X, Y, Z
  
  
• Bottom right - Extruder: stepper+fan+heating element - the pins are:
  
  |——\__/——————————————|
  | HP HN FP FN 2B 2A 1B 1A |
  |——————————————————|
  Where:
  HP/HN - Heater positive/negative
  FP/FN - Fan positive/negative
• Middle right - active cooling fan, not using it for now to keep things simple
• Top right - thermocouple, not used, using a Thermistor
  

In the end the connectors that I need were: steppers, endstops, extruder