It should work.
Ctrl S to get the sidebar back in the new itunesThen they look similar
Ctrl B to show top menu
In itunes 11 to turn on Home Sharing
File > Home Sharing > Create Home Share
Enter the apple id and password
in iTunes 10 Advanced > Create Home Share
Enter the same apple id as above. It does not matter what Apple ID they are lofgged into itunes store with
On each machine you should now see a house shaped icon showing the other machines library under Shared in the left hand sidebar.
If the 2 machines use different Apple ID to purchase from itunes you need to authorise each machine with the other account. If it is the same ignore this
Then you should be able to select the library from the other machine and import.
I have just checked this on a machine with iTunes 11 on it and another one with iTunes 10.7