Set up a domain in your nginx/caddy/whatever configuration for the idp(1) server
Set up idp(1) to listen on a local port: ./idp -port 5484
Generate a TOTP key: ./idp -secret-gen 16
Make a config file
Configure idp to start on boot: idp -config /etc/within.x/idp.conf
Add <link rel="authorization_endpoint" href="https://idp.christine.website/auth"> to your homepage/index.html where idp.christine.website is your domain from the second step