network install create/mount iso

create iso from dvd:
dd if=/dev/dvd of=/var/www/html/centos/CENTOS5.iso

mount iso “into” an accessible directory
mount -o loop /var/www/html/centos/CENTOS5.iso /var/www/html/centos/src/

make an iso from a directory
mkisofs -o /path/to/directory.iso /path/to/directory/