Watchface : preferences

Is it possible for a watchface to have user preferences?

For example, allow the user to say tap the screen to bring up a Config page that allow them to set the date format dd/mm/yy or mm/dd/yy or to set the colour scheme, i.e. black on white or white on black.

So I don't have to have many versions of my watchface.

Obviously these settings would need to be persisted somewhere. Is that possible?!

Thanks.