I bought a 2011 Mac Mini, which came with Lion installed. I thought maybe I could repartition it and have a Snow Leopard partition. So I repartitioned it (500gb split into two 250gb partitions). I named the new partition "SnowLeopard" just to make it easy for me to tell the difference.
I attached the external DVD and put in a Snow Leopard installer disc, holding down the C key so it would boot and install from that, but it just spun for awhile. Doesn't appear to work.
Then I read somewhere else that someone had managed to clone a copy of Snow Leopard onto an external drive and boot from that. In their situation they were talking about a MacBook, but the principle seemed sane.
So I rebooted, holding down the T key to put the Mac Mini into Target hard disk mode, and attached it via Firewire to another MacMini (circa 2008 or so, not sure of year, but it was upgraded last year to Snow Leopard and has been upgraded along and along). Then I used Carbon Copy Cloner to copy Snow Leopard (that is, the entire hard disk-- System and all applications and data) to my newer Mac Mini's "snow leopard" partition.
For yucks, when it was done cloning, I restarted the older Mac Mini, and had it boot from the newer Mac Mini's snow leopard partition--- it worked! To make it easy to tell the difference, I changed the desktop background to something completely different. I think I tried booting from Lion but I can't remember if that worked.
Then I rebooted the newer Mac Mini, which booted up in Lion, of course. Going into System Settings, I changed the startup disk to the "snow leopard" partition, and rebooted, and it booted up in Snow Leopard.
I have yet to test the applications on the Snow Leopard partition. Another problem has arisen.
Because with both of the Mac MInis being active on the network, they both had the same computer and user name. So I renamed the newer Mac Mini to something completely different, and changed the password.
Unfortunately, now I cannot change any other setting in the System Settings that requires a password. While the newer Snow Leopard lets me log in with the new user and new password, whenever I try to click the "lock" icon to change something, I'm prompted for a username and password. Apparently this is some different username and password than either the new or old username/password.
I've tried various combinations of both: new user/old password, old user/new password, old user/old password, etc.
So if you do what I've done, be careful about changing the username and password on your cloned computer. I think it may be wiser to create a new user and then delete the old cloned users. I may just have to re-clone the old Mac Mini to the new one again.
If anyone has any ideas about this password conundrum, please pass along!