Hi CC - you're asking the wrong person - double_ohh7, Drew Reece, and Rustyintegrale seem to be the experts and hopefully one of them will step in to help..
in the meantime, -
i installed 10.7 on my new iMac, and quickly upgraded to 11. .. hated it so i copied the .itl file from my old macmini, and used that in the method described in the link posted by double_ohh7, further up this thread.
everything worked fine.
i guess that a backup of your new machine with 11 would be a good idea, though only if the procedure goes wrong for some reason (like a power cut!)
i'd suggest that you make a list (perhaps a smart playlist) of any songs added since you started using 11, as you will lose the link to them, but you'll be able to re-download them from the iTunes store IF you know what they are!
good luck
Paul