Here are a few pieces entirely composed in µO:
Tout va bien (merci), Ressac, Bulle qui rulle, Rauquosphère, Lithorale, Blue glue, I'll get there, again, Day one, Busy Claude is late again, Tannit.
Download the ready-to-go 335 image archive, unzip it anywhere and start
That's it; you don't need the following instructions.
squeak.exe: you will see the Squeak window.
muO.***.sarfile, and start again from a new copy of the base folder.
muO.***.sarpackage are available on SqueakMap.