Booting from clone on a different computer

I made a clone of my MBP Tiger system using superduper to an external drive before upgrading to Leopard on the MBP.
I also have a Mac Pro running Leopard.
I would like to transfer just my emails in Mail from the MBP clone image to my Mail inbox and sent folders on my Mac Pro.
The rest of the clone doesn't interest me and I plan to wipe it out and create a new clone of the MBP after it is all set up running Leopard.
Migration assistant didn't seem to allow me to do just this so I didn't use it.
Can I connect the external drive with the MBP clone image to my Mac Pro and boot from that without creating problems because it is another computer with different hardware?
Can I then just export those Mail folders and then import them into my Mac Pro's Mail folders?
If doing it on the Mac Pro is impossible, can I boot from the clone with my MBP now that it is running Leopard and export the Mail folders there then just transfer them to the Mac Pro?
Thanks for any advice.