You don't need to refactor the existing code. You can change the calling code.

    // Promisifying a standard callback
    const myAsyncMethod = Bluebird.promisify(myCallbackMethod);

    // Or if you have weird callback passing and need
    // to manipulate the callback method being passed around
    function myAsyncMethod(...args) {
        return Bluebird.fromCallback(cb => myAsyncMethod(cb, ...args));
    }