Here you will find information on how to add single outputs to your beloved Minipops-120.
This mod is compatible to midi added with the uniPulse. An uniPulse installation manual for Korg Minipops 120 is here.
Attached is a picture (extracted from the service manual) of the circuitboard and the points/parts you have to desolder to add single outputs. The HighHats and Cymbal share the same output, so you will get 7 single outputs for Bassdrum, Snaredrum, Claves, High Conga, Low Conga, Bongo and Highat/Cymbal.