Install Leopard on an External Drive on a Snow Leopard Mac Book Pro

Question

Hi
I have a MBP 17/CTO 2.66GHz i7, which came installed with Snow Leopard.
I've used boot camp to install Windows 7.
I've attempted to install Leopard 10.5.4 on an external drive.
The steps I've taken:
1 - Connected my WD Passport on the Firewire Port
2 - Partitioned the drive. The first partition is 100GB, Mac OS/X Extended (journal) and I've selected the GUID Partition Scheme
3 - Inserted the Mac OS/X Leopard DVD, and followed the instructions to restart
4 - On restart I have three options. Mac OS, Windows and Install Mac OS\X
5 - I select Install Mac OS\X.
6 - The disc spins for a few moments and then the laptop freezes
Beware of the following issue:
1 - On restart more often than not, the DISC will spin and then the laptop will freeze.
2 - To overcome this, restarting pressing the ALT (option) Key.
3 - You should see your boot options. If you do not see "Install Mac OS\X", then eject and reinsert the disc.
The question maybe why would I want to have an Leopard Installation when I have Snow Leopard. The software I develop has thrown up a number of differences between Leopard and Snow Leopard, hence I need both OS's to support my software.
I mentioned this to the Apple Store before I purchased my machine. They put me through to a senior technician at Apple Care, who told me it would be possible to have the set up I am after; and to contact Apple Care if I ran into any difficulties.
After I received my laptop and ran into the problems I described above I contacted Apple Care, only to be told by a senior technician that it should be possible to install Leopard on an external drive, but Apple Care cannot provide any support or assistance.
I really do like the laptop and would much rather not return the laptop; but I really do need the setup described.
Anyway I have tried a number of different approaches:
1 - Having no partitions (so just the single partition)
2 - Trying all three Partition Schemes:
- GUILD Partition Table
- Apple Partition Map
- Master Boot Record
All resulting in the same problem.
I can confirm the external drive does appear as bootable in disc info.
My guess is one of the following is preventing the install:
1 - It is simply not possible to install an earlier version of Mac OS\X than 10.6 on the laptop I have, even if I tried to install on an external drive. This restriction is built into some hardware confirguration. So even if I wiped the internal hard drive or added a new partition to the internal hard drive, I would not be able to install 10.5.4. I say this may be a reason as the second technician told me the CPU has built into it a process which prevents installing older versions of Mac OS/X, but that it should NOT restrict installation on an external harddrive.
2 - When trying to install Mac OS/X, a search is carried out for an external drive which has the correct format. For some reason it may be that this search is not finding my external drive?
I'm a little stuck here and quite disapointed that the support promised by Apple Care for assistance in setting this up, is now not forth coming.
Any help or suggestions would be appreciated, as ideally I would prefer to keep and not return the laptop, it's a beautiful piece of machinery.
Cheers
Parmy

Answer 1

The mystery continues...
I have an older MBP (2.33 GHz Intel Core Duo) which came installed with Tiger. I can confirm I purchased a genuine copy of Leopard (10.5.4) from the Apple Store and it’s not an OEM version. I installed 10.5.4 without a hitch on my old MBP internal drive. It is the only OS installed on my old MBP.
Using my older MBP (which through software updates is now running 10.5.7), I managed to install 10.5.4 onto my external HD (WD My Passport Studio – 640GB FireWire 800).
However; on the final restart, the screen remained grey and 10.5.4 did not boot from the external drive.
I restarted the machine holding down the ALT (option) key, and only two options appeared, Macintosh HD and the Install DVD. I selected the Macintosh HD and opened System Preferences.
In System Preferences --> Startup Disk, I discovered the partition on my external HD which contains 10.5.4. I selected this partition and selected restart.
On restart my MBP displayed a grey screen, and the blue light on my hard drive flashed slowly. I left this for an hour, however; the OS did not start and the screen remained grey.
I then plugged my external HD into my new MBP which I started holding down the ALT key.
To my surprise I found 3 boot options (Macintosh HD, Windows and Leopard). Leopard being the partition on my external drive, which now has 10.5.4 installed.
I selected Leopard, but sadly after 30 minutes, the OS failed to boot.
Although this deviates slightly from this post, I fail to understand the problem here:
1 – Why can’t I boot 10.5.4 on an external drive, from my old MBP? Surely this is not because my old MBP is now running 10.5.7?
2 – Why can I see 10.5.4 as a boot option on my new MBP but not on my old MBP when I start the MBP holding down the ALT key?
I doubt there is a problem with my external drive, as it seems to read, write, etc... in all normal cases.
Whilst it definitely appears that I won’t be able to boot 10.5.4 on an external drive from my new MBP, I should be able to at least boot it from my old MBP, which would give me the option of installing Snow Leopard and Windows on the internal drive of my old MBP.
Apologies for keeping this post going, but I hope by getting to the bottom of this, it will help other Mac users as well.
I’ve run out of ideas of things to try, so I will give Apple Care another call in the morning, and will report back.
Any suggestions of other things I can try?
Cheers