9.1 running on 10.4

Exactly which model and year Mac are you attempting to install on?

Link to give you a broad picture of running classic.

http://en.wikipedia.org/wiki/Classic_Environment

http://support.apple.com/kb/TS1929

I found a link to a discussion on Installing classic mode on Tiger. Some of the simple things like dragging a OS 9 system folder would be worth a try. This would not affect the OS X installation onn the drive.

https://discussions.apple.com/thread/3638622?start=0&tstart=0

The best setup for Tiger and OS9 is to partition the hard drive into two partitions one for OS X and the other for OS9.

I had a Pismo G3 powerbook set up this way and was the best of all worlds. Tiger was the default OS and classic mode was readily available but had some limitations due to the emulation interface. By holding the option key at startup I could choose OS X or OS9 from the startup partition. This way I could run OS9 natively for better performance.

This was from poster Limnos in the link.

"If all you have are installer versions of OS9 on optical that is where you may run into trouble and may ultimately end up needing copies of the original discs (which likely are no longer available). You will have to get the computer to boot to the installer disc in order to get it to actually put a usuable copy of OS9 on the computer. "

You are likely going to need the original installer disks or copies of them.

If you have the install disks it would be one of them. With the utility Pacifist you can extract the individual app/file/folder and reinstall.

http://www.charlessoft.com/

Pacifist is a shareware application that opens Mac OS X .pkg package files, .dmg disk images, and .zip, .tar, .tar.gz, .tar.bz2, and .xar archives and allows you to extract individual files and folders out of them. This is useful, for instance, if an application which is installed by the operating system becomes damaged and needs to be reinstalled without the hassle of reinstalling all of Mac OS X, or if you want to inspect a downloaded package to see what it will install before installing it. Pacifist is also able to verify existing installations and find missing or altered files*, and Pacifist can also examine the kernel extensions installed in your system to let you see what installer installed them, and whether the installer was made by Apple or a third-party.

Pacifist is compatible with Mac OS X 10.4.11 or higher, including Mac OS X 10.8 “Mountain Lion”. It is also compiled as a Universal Binary for maximum performance on both PowerPC and Intel-based Macs.

I'm not sure what all this means and can only suggest to try log in as Root and see if that allows it to run. I haven't done this for years so here are some instructions. Good luck. 🙂

http://support.apple.com/kb/ht1528

http://www.spy-hill.com/~myers/help/apple/EnableRoot.html

http://www.howtogeek.com/howto/35132/how-to-enable-the-root-user-in-mac-os-x/