Booting into rescue mode from the RH6.2 CDROM, it is not possible to mount a system's filesystems because the /dev directory lacks device nodes for the hard drives. It also lacks MAKEDEV and mknod, the utilities that would allow the creation of device nodes. This generally renders the rescue mode useless since it doesn't allow the system being rescued to be accessed.
just type "mknod /dev/hda" and you get a /dev/hda node just type "mount /dev/hda1 /mnt/sysimage" and all the devices and mountpoints are made for you.