This workaround solution is much simpler than the cookie injection.
1 Use your favorite browser to go on the login page and authenticate.
2 Copy the full URL from the browser URL bar.
Example: http://www.mywebsite.com/index.jsp;jsessionid=12345
3 Paste the full URL value in your favorite text editor.
4 Using the text editor, copy only the session token and make sure you get the semi-colon as well (;).
Example: ;jsessionid=12345
5 Log into your account and go to Account > Web Applications on the left menu.
6 Select the New link and add another another instance of your web application, appending the session token to the URL in the Starting URI field. Make sure that the starting URI contains a web page before appending the value.
Example: http://www.mywebsite.com/menu.jsp;jsessionid=12345
7 Click Save.
Now you are set. Remember, like the session cookie the session token might be valid just for a limited period of time. However, the session token might live for a longer time before dying.