streamline.js already fits the bill, including your golden rule: the core idea was precisely to generate the callbacks that the developer would write otherwise.
Today it works with both CoffeeScript and Javascript, but in a decoupled way: the streamline transformation is applied to the JS generated by the CS compiler. It could easily be repackaged as a CS language extension.
It has been around for more than a year and the CS+streamline combination is powering at least one live site: http://www.thethingdom.com/