Also inside that LilyPond engines directory is a README.txt file,
which actually has instructions on how to enable point-and-click!
(Federico, take note.) I’ll just copy and paste the instructions
here:
1. Install the SwiftDefaultApps pref pane from
https://github.com/Lord-Kamina/SwiftDefaultApps
2. Open GotoTeXShop.applescript in Script Editor. [also included in
the LilyPond engines directory]
3. Go to File > Export…
4. Choose Application as the File Format.
5. Save GotoTeXShop.app.
6. Go to the SwiftDefaultApps pref pane and choose GotoTeXShop.app as
the
handler for textedit URI Schemes.