If your "override" window will not come up for a blocked website, here are some things to try.
1. Go to http://mps.org to open the override for the block.
2. Click on this link: http://10.9.0.29/restricted/block/login.html?ibip=205.215.144.19
3. Take out the "s" in the "https://" then the block should come up. 75% success rate
4. Go to http://icanhascheeseburger.com and the override window will come up.
Once you can view the window, login with your MPS username and password.