First, replace /Users/james with /Users/<your_username> in deployment/com.everythingisgray.rat-man.plist. Next, replace confidently-realistic-replete-alewife-bb3 with your own device ID and RatManClock with your own installation ID. Finally, replace event_time and event with your own event time and event in run_rat_man.sh.
brew update && brew install tidbyt/tidbyt/pixlet
pixlet login
cp deployment/com.everythingisgray.rat-man.plist ~/Library/LaunchAgents/
launchctl load ~/Library/LaunchAgents/deployment/com.everythingisgray.rat-man.plist