how to show PHP as a text?

Hi, I was wondering if it is possible to create a button which would works as [PHP] button in this forum at control panel.

Because I need to show PHP to users when I am commenting. Also would be great to post javascript, css...

Regards, Aurimas. :)

http://php.net/manual/en/function.highlight-string.php

in that place is one example, but I didn't understand it... How it will detect that in my message ($zinute) is PHP script and highlight it?