In order to open an application in a Schoolbox iframe you must use the following URL in Schoolbox - http://schoolbox/modules/remote/{base64encodedURL}
The URL you wish to be loaded should be base64 encoded on the end of the string.
You can optionally add /window on the end of the URL to open the page in the complete window rather than an iframe. This will open the page you want in that window without any of the Schoolbox interface around it - Just like opening it up directly on that page like you would with any other link regularly (such as a link you search for in google). The authentication will still work this way too, just in case you were wondering! If you didn't apply the /window, it would open embedded in an iframe with the Schoolbox interface still there.
To encode your URL use the following online tool. http://www.freeformatter.com/base64-encoder.html
If you wish to control the height of the iframe. You may optionally include the parameter (zx_h).
For example before base64 encoding the url.
http://google.com.au#zx_h=800px