Here's how I did mine:
Original Homelink from my ex Mitsubishi Eclipse '98 GSX:
Note: This photograph does not belong to me.
Homelink Taken apart for soldering wires:
Homelink assembled with RJ-11 wire sticking out:
Buttons & LED assembled and housed on the monitor's bezel:
[Homelink on the left, PC Reset & LEDs on the right]