is it possible to run both fastcgi as well as mod_php at the same time? im guessing fastcgi can be used by just setup his .htaccess file to have the user a choice whether which to use?
Yes, you can If you want to have PHP4 as fcgi and PHP5 as mod_php - set php4_cgi to yes, and php5_cli to yes in the options.conf file. Read CustomBuild FAQ (http://directadmin.com/forum/showthread.php?t=19221) for more information.