I can confirm it is definitely not there. Then again, I can't find a register button on that stupid trac either.
I am using Firefox 3.0.2 on Fedora 9 Linux. The server is CentOS 5.3 with PHP 5.2.9 and MySQL 5.0.77.
There is definitely no relevant button at step 3 in the install. I read somewhere that there should be an "Initialize Database" button on this screen. I did text searches of the HTML source even to confirm that it is not there.