laotse on "Set own _wpColorScheme"

Analysing the code I found that admin_color_scheme_picker sets the JavaScript variable _wpColorScheme apparantly to dynamically shade icons. My theme uses its own color scheme, but it may be a good idea to use this mechanism as well. So I tried to use my own function:

remove_action('admin_head', 'wp_color_scheme_settings');
add_action('admin_head', 'my_backend_color_scheme');

but apparently it is still wp_color_scheme_settings, which is executed and not my function.

Any ideas why this does not work?

Is there probably a more appropriate interface to define one's own color scheme? (I hate to modify my CSS for each new version of WP)

Thanks,
- laotse.