How to access the Express logger in Kraken

Question

I'd like to set up Winston logging in my Kraken-based app, but I am not sure how to get a handle on the express logger object to set up the stream for it.

index.js:

// enable web server logging; pipe those log messages through winston
var winstonStream = {
    write: function(message, encoding){
        winston.info(message);
    }
};

app.requestStart = function requestStart(server) {
    // Run before most express middleware has been registered.
    app.use(server.logger({stream:winstonStream}));
};

[TypeError: Object function app(req, res, next){ app.handle(req, res, next); } has no method 'logger']