How can I create a HTTP POST request with some URL encoded parameters using Qt 4.6.1?

I figured out that I can create a QNetworkRequest, set all the parameters there and send it via QNetworkAccessManagers post method. But how can I add some URL-encoded parameters to the request?

In the end I want to access the Eve API using Qt/C++. A Python example can be found here: http://www.eveonline.com/api/doc/example-python.asp

I managed it using something like (still to be refactored and formed into something useful):

QNetworkReply *requestApi(QNetworkAccessManager &nwam)
{

    QNetworkRequest request(QUrl("http://api.eve-online.com/account/Characters.xml.aspx"));
    request.setHeader(QNetworkRequest::ContentTypeHeader,"application/x-www-form-urlencoded");

    QByteArray data;
    QUrl params;

    params.addQueryItem("userid","user");
    params.addQueryItem("apiKey","key");
    data.append(params.toString());
    data.remove(0,1);

    QNetworkReply *reply = nwam.post(request,data);
    return reply;
}