This light is made of two SparkFun Lumenati-8 modules controlled by a Raspberry Pi Zero W. The Pi runs HomeKit server implementing the non-commercial HAP spec.
The light also has a joystick attached to the Pi through ADC so the LEDs can be controlled either locally or remotely from a phone.
Assemble hardware accordingly to one of schematic diagrams below.
Prepare RPi SD card, boot up the Pi, and configure it for WiFi.
Log in to Pi and install HomeKit Accessory app RpiHap as documented here.
Ensure that RpiHap is running and try control the light using joystick. Pushing it down turns light on and off, its vertical channel controls brightness, and its horizontal channel controls hue.
Open the Home App on your iPhone or iPad and pair it with RpiTest accessory. The setup code is 000-11-000.