I'm not big into web dev either, but I've never heard of being able to control that via .htaccess before (and allowing suid to any user other than the owner of the .htaccess file to be configured that way has obvious security problems). Apache does, however, have suexec, which I believe causes scripts to run suid as their owner. AFAIK, suexec is the only way for CGI/etc. scripts to run as a user other than the apache user.