[QUICKFORM] Which PHP version is required for QuickForm to operate?

Hi! Our provider has PHP version 4.0.6. I am wondering if I can use QuickForm (and consequently, whether HTML_Common and Pear classes will be able to operate) in this environment. I read that $_GET, $_POST and $_FILES were added in PHP 4.1. Do you think if I tweak the code replacing them with $HTTP_ variables, will QuickForm work? Or are there other functions that may be dependent on later PHP versions. The inline documentation before HTML_QuickForm class declaration says "@since PHP 4.0.3pl1", but I think that's not very accurate, since PHP documentation states that $_ variables were added in 4.1. Thank you very much! Stanislav