need to switch to mod_php

Much of my code was broken by switching to mod_fcgid. Our clients websites have an admin facility that uses browser authentication variables (PHP_AUTH_USER, PHP_AUTH_PW) passed to the environment in mod_php to determine the admin level of the user to give different levels of access to administer the websites. This is a critical feature that our clients rely on. Is it difficult to switch back to mod_php? I need clear instructions to accomplish this. Much as I like the idea of having suexec on the individual virtual domains, I do not have time to recode all of the admin facilities! I have no choice but to change back.