just if someone else need it:
Code:
var user = "your username";
var passwd = "the password";
var fakturaurl = "the url of your service";
reqUrl = ZmZimletBase.PROXY+fakturaurl+"&auth=basic&user="+user+"&pass="+passwd;
AjxRpc.invoke(params, reqUrl, reqHeader, new AjxCallback(this, this._resultCallback, [ service ]), false);
I recommend you just use SSL
