What really works
I just tried quincymc's suggestion of deleting the file at:
/System/Installation/Packages/BaseSystem.pkg/Contents/Resources/InstallationCheck
and removing:
eraseOptionAvailable='true'
from the file OSInstall.dist, and it doesn't work--the installer still reports "This software cannot be installed on this computer". I wish he'd reported back here that it didn't work for him either, before I wasted several dual-layer DVDs trying that and variations on the idea, including changing "true" to "false" instead of deleting the entire "eraseOptionAvailable" section, but that didn't work either.
I was hoping that just removing the InstallationCheck file would do the trick, so I also burned a DVD with just that file deleted, and without making the change to the "eraseOptionAvailable" variable, but it didn't work--I had a feeling it wouldn't, since that wouldn't do anything to the model-checking code inside OSInstall.dist file (I dont know why there are two files involved in model checking).
I did some Googling to try to find the inspiration for quincymc's suggestion, but found nothing except links pointing to this forum thread, and a few pages in languages other than English, which Google translation didn't translate in a way anybody could understand.
What does work, is posted at:
http://fraserspeirs.livejournal.com/2006/10/15/
Here, the author describes how to add a Mac's machineID to the list of supported Macs--no removing InstallationCheck, and no removing "eraseOptionAvailable='true'". Adding a Mac's machineID to the OS X installer's list of supported Macs is the right way to do it (in fact, the only way for later versions of the OS X installer for later Macs like Intel Macs--earlier OS installers just require you to REMOVE the target Mac's machineID from OSInstall.dist's list of "bad" machines), since then you can make an install disc that will work only on Macs that were released at or before that install disc was released; or you can add all the machineIDs that exist, and install onto anything. However, though installing an earlier OS on later Macs that require a later version might work, as long as the Combo updater that you can run after installation fills in the blanks, we can't be certain that will always work, so whenever possible, if you don't have the proper version of the OS X installer discs for a Mac, then modify a version for a later Mac model (maybe preferably a MacBook or MacBook Pro installer so it installs any MacBook-specific code, which a desktop installer version might not--someone correct me if I'm wrong), and then, after installation, run the latest Combo updater to make sure anything that didn't get installed, does. Though that's worked fine for me to make a boot drive that works on any Mac model that can boot whatever system version I'm installing, that's no guarantee.
I just tried Fraser's suggestion, using the install discs for the original MacBook Pro (machineID 'MacbookPro1,1'), on an original MacBook (machineID 'MacBook1.1'), and it worked fine.
Here's what Fraser says, with my additions and corrections:
1. On the machine you want to install onto, find the machineID by entering this into Terminal:
sysctl hw.model
You can also use the utility "MacTracker", which lists the machineID for most Macs. The original Macbook, which quincymc was trying to install onto, has a machineID of MacBook1,1.
2. Use Disk Utility to make a read/write image of the first DVD in the software install/restore set.
3. Mount this image--use Disk Utility's "Open" command.
4. Edit the file at /System/Installation/Packages/OSInstall.mpkg/Contents/OSInstall.dist (TextEdit will work fine):
Do a search for the line that starts with:
var hwbeSupportedMachines
5. Add the desired machineIDs to the hwbeSupportedMachines array, after the machineID that's already listed--add a comma, then the new machineID enclosed in single quotes--for example:
['MacBookPro1,1','MacBook1,1']
6. Save the file.
7. Unmount the disk image.
8. Burn the image onto bootable media. You can use Disk Utility to restore the image to a partition on an external hard drive, or you can use Toast to burn it to a DVD--it's a dual layer, so that's what you'll need to use.
8. Boot the 'unsupported' machine from your hacked installer.
If you're dealing with an Intel Mac, remember to erase the drive as GUID format, or the installer, even if hacked properly, will report at the volume selection window, "You cannot install Mac OS X on this volume. Mac OS X cannot start up from this volume."
You might also want to try the suggestions by Guy Merritt at:
http://jonsharp.net/archives/2005/05...er-on-lombard/
where he describes other mods to make to OSInstall.dist, to turn the installer into an even more universal installer. Jon Sharp's original post at that link, describes how to modify the OS 10.4.x installer to make it work on much earlier Mac models like the Powerbook G3 Lombard (remove the Lombard's "bad" machineID from OSInstall.dist), but Merritt describes well the process for more recent Macs.
