build new portal or new security without any risks ?

The best way to test a pre-login sequence in a production environment is to set the very first check to be something obscure/unique/impossible for a normal user to meet and then set the fallback end page to Logon Allowed.

 

 

This will allow you to set your test machine to meet the obscure condition (made-up registry keys are probably the easiest) and therefore traverse the more complex portion of the pre-login sequence that you're looking to test out.