The only way to avoid the warning is to purchase private SSL.
Here is how you can bypass the warning if you want to use the shared SSL.
Firefox
- Go to the warning message and click the "I Understand the Risks" link at the bottom.
- Click the "Add Exception" button.
- Click the "Get Certificate" button.
- Click the "Confirm Security Exception" button.


Internet Explorer
- Go to the warning message and click "Continue to this website (not recommended)."