Well, I'm stumped. I have a new (Nov 2011) i5 mac mini, that is giving me #@*@ with its refusal to output 5.1 sound via HDMI, and so I tried to install SL to a spare firewire disk on the mini from a remote-mounted retail SL 10.6 DVD (part no mc2232Z/A). The SL installer won't run from the mini - says it needs a different version of the application.
So I copied the SL install disk to a USB stick, and tried to boot from that. Got a kernel panic. Might look deeper into that, but I don't know what to look for.
Don't have a MB Pro to use for the target disk trick, but that seems to be the key.
Mike