This layout attempts to keep all special keys in place as far as possible, so that only the core Colemak layout has to be learned. "ö" and "ä" had to move one place to the right.
Here's the layout with the Option key held down:
Note that Alt+l (@), Alt+e (€), Alt+u (¨), Alt+n (~) etc. also moved to the new Colemak positions.
The Windows version was created using keyboard-layouts/mac2winKeyboard.py. It shows up with a strange name (containing "Mac"), but seems to work as expected.