There is a thread that discusses using IsoBuster to create an image. You need to back up the entire hybrid disk (at least for 10.6).
Can you access another Mac to do this? If so, in Disk Utility select the drive (not the volume) and click the New Image button on the toolbar to save a DMG as a DVD/CD Master. Funny idea: go to an Apple Store with an 8 GB or higher USB stick, buy Snow Leopard, then use one of the computers there to create the DMG.
Once you have the DMG, rather than using diskutil at the command line, just use Disk Utility and create a 10 GB partition at the end of your drive (under the Partition tab for your drive). Then go to the restore tab and select the DMG for the source and the new partition for the destination. Make sure Erase destination is checked and double-check that you're dealing with the right partition.
Note that I'm using Disk Utility on 10.6 and I haven't worked with 10.4 in a long while. My thinking is that Disk Utility hasn't changed very much and I hope that the features that I'm talking about exist and behave as I would expect on 10.4.
Finally to install Snow Leopard, reboot your computer, hold down the ⌥ key as soon as it starts up (chime) and you should be presented with two options, both with a hard drive icon. The second option should say Mac OS X Install DVD. Select that.
EDIT
Specific IsoBuster instructions from the above thread:
Open IsoBuster -> right click "DVD" on the left side -> choose "extract dvd " -> User Data (*.tao, *.iso)
Name the file whatever you want (ie "Leopard") on the "Save as type" choose ".iso"
Click Save and wait for image to be created. After it is finished it will probably ask you to save a ".cue" file as well...go ahead and save it, but you should not need it.
The best backup/archive policy is 3 copies: 1 primary, 1 backup in case the primary fails, and 1 off-site in case of a fire or such.
Best Answer
Losing a copy of PS:T would be a great loss to the world!
Recovering with ddrescue
I suggest you attemt to use ddrescue to recover what you can from the disk. If you run *nix it will run natively and is likely in your package manager or what have you not (macports?), otherwise it's included in many Linux live disks, some are listed in this thread.
You should have a look at the ddrescue manual, but a basic example (Example 3 in the manual) for recovering a cdrom is
You might want to add the option
-r [number > 0]to try reading more times, and-Sor-pfor convenience.You should then end up with an "iso" image of the disk, which you can then burn to a new cd-r or use with some disk emulating software.
Reducing the cdrom speed
As @ChrisF mentioned, spinning a damaged cdrom up to high speeds might not be the wisest endeavor, and it certainly won't help the rescue effort (it's generally easier to read the text on slow moving cars, right?).
I have no idea how to reduce this on MacOS, but most Linux distros let you use the eject command to reduce it, like so
Unless I'm very mistaken, a cd speed of
1xis approximately one rotation per second. I can't really test how this output looks, since this computer doesn't have an optical drive.You probably want to choose the lowest available speed. Make sure you do this before you try to recover with ddrescue.
Closing
Unfortunately, there is a very real danger that you will lose some data in this process. This might have different consequences, though I believe DRM complications won't be an issue, general data errors might be a problem. Bit errors in textures are not really a big problem apart from looking bad, but damage in the binaries might be fatal. Assuming you can install at all, you might be able to extract non-broken files from the GOG.com release of PS:T (English, available at 10 USAian bux), although that would likely be a major undertaking. Alternatively, you might be able to copy savegames between the versions to play through broken sections. (This is just speculation on my part.)