Here are the photos from my tear-down of the Sony ICD-UX70.
After getting the unit disassembled, I soldered wires onto each of the transport buttons so I can control it with an Arduino.
I tested the unit with the microcontroller — and two control techniques are very promising. I can either use pull-up resistors and connect the microcontroller outputs directly to one side of each switch (the 3V side), or I can use NPN transistors to bridge the terminals on each switch and use the microcontroller to control the transistors’ bases.