How to add a sandboxed app to the login items

I want my app to auto start if the user select the option. The methods I have been using is not allowed anymore in sandboxed apps.

I know I have to create a helper to achieve that? Is there a simple tutorial with sample code to active that?

I found this tutorial, but it does not work for me: http://www.delitestudio.com/2011/10/25/start-dockless-apps-at-login-with-app-sandbox-enabled/

It is a pretty standard thing to do, I don't understand why there is no example project available.

UPDATE:

I uploaded a sample project: http://ge.tt/6DntY4K/v/0?c

Solution

You should succeed by using this (disclaimer: my) tutorial, sample project included.

Update: I've now tested the sample project you've uploaded: It works just fine with me, without any modifications, and launch at login succeeds. The only trick is that the AutoStart.app file has to be placed in the /Applications or ~/Applications folder to be launched successfully at login. This is necessary regardless of whether the app is sandboxed or not. However, there's no official documentation on this, I'm afraid.