Setup

Download the .crx file of the LINE Chrome extension (version 2.4.1), and extract it to puppet/extension_files
cd to the puppet directory and run yarn --production
Run node prep_helper.js to open the version of Chrome downloaded by Puppeteer, and click on the LINE icon next to the URL bar
Once the LINE popup appears, press F12 to show DevTools, which will reveal the LINE extension's UUID
Copy puppet/example-config.json to puppet/config.json, and update it with the UUID found in the previous step
Launch the Puppeteer module with yarn start or node src/main.js
cd to the main directory and create a Python virtual environment with virtualenv -p /usr/bin/python3 .venv, and enter it with source .venv/bin/activate
Install Python requirements with pip install -r requirements.txt
Copy matrix_appservice_line/example-config.yaml to config.yaml, and update it with the proper settings to connect to your homeserver
Run python -m matrix_appservice_line -g to generate an appservice registration file, and update your homeserver configuration to accept it
Run the bridge with python -m matrix_appservice_line
Start a chat with the bot and follow the instructions