No, I don't think it's possible...otherwise, what's the point of the time limit if you can get around it 🙂
But if you are not running the PHP script from the browser, then look at the command line arguments for the PHP parser. I believe there is one argument that allows you to specify the php.ini file. Therefore, create another php.ini file with unlimited execution time and let PHP use that ini file instead of the default one.
Diego