Boot old 10.6.8 install from USB drive on iMac Late 2012

[simonjones88]

I'm hoping someone can help with an issue I'm facing.

I recently upgraded from a late 2006 MacBook running 10.6.8 to a 27" iMac Late 2012 running 10.8

The MacBook is pretty much dead. It overheats, buzzes, hangs - hence the upgrade.
My problem is I can no longer use my copy of Logic 8 so I'm looking for a way to boot the old 10.6 install on the new machine.

Upgrading to Logic 9 isn't an option, as I work on projects with a partner who uses 8. We need to move between each other's setup, me upgrading would render his version obsolete.

I have removed the MacBook Hard Drive and put it in a USB 2 caddy, it mounts fine on the new machine under OS X 10.8, but I can't work out how to boot it.

I have tried:

• Setting startup disk to 10.6 HD in a USB 2 caddy - this gets to the grey Apple logo and hangs (I left it for an hour)
• Virtualisation in Parallels and VM Ware Fusion - I can't find options to boot from physical boot drive
• VMWare/Parallels restore from 10.8 restore partition, then use startup disk when it loads and connect USB and use startup disk from there - reboots to restore partition again or says "not OS X Server powering down"
• Making a .dmg of my 10.6 install disk to install on Parallels/VM and go form there - install disk image doesn't work either

There must be some way to get it to boot the old drive on the new hardware, directly or virtually
Any help appreciated...

Thanks,
Si