hey, copy the install script to your home directory. Open a shell and change into that directory.
type:
SETUP=/dev/sr0
(or whatever device your cdrom is...check your fstab.)
then run the install script.
sh linux_installer.sh
Then the install script should mount and unmount your cdrom for you if you did the SETUP command above.
after you launch the installer, no matter what disk it asks for. start with cd 1 and go through to 3. whoever wrote the install script got a little mixed up on what cd to ask for.

Probably the solution to this problem
 

Hi,

I was having this problem myself but none of the suggestions worked.

Then I noticed that some of the filenames on the CD were cut off (they were all in DOS 8.3 format).

I found out it was because I didn't have Joliet extensions support for ISO file system. So I reconfigured the kernel to enable this, rebuild the isofs kernel module and it worked immediately.