Here's some info... right from the online manual... I hope it helps:
Adding Apple Loops to the Loop Browser
Logic Express must index Apple Loops before they are shown in the Loop Browser.
Loops can reside in any directory, but you need to tell Logic Express where to find
To add Apple Loops to the Loop Browser:
1 Open a Finder window alongside Logic Express.
2 Navigate to the folder that contains the Apple Loops.
3 Select the Apple Loops in the folder and drag them into the Loop Browser.
The loops are added to the Apple Loops library and indexed. When this process is
finished, the loops will be available directly in the Loop Browser.
If you drag a single loop to the Loop Browser, the loop will be copied to ~/Library/
Audio/Apple Loops/User Loops/SingleFiles.
If you drag a folder of loops that are located on the same drive and partition as the
Loop Browser, the loops will be left at their current location, and an alias of the folder
will be created in ~/Library/Audio/Apple Loops/User Loops.
If the loops are located on a different drive or partition, youâ??ll be asked whether you
want to copy them to the loop library, or index them at their current location (loops
added from optical media will always be copied).
AÌ? If you choose to copy them, the folder containing the loops will be copied to ~/
Library/Audio/Apple Loops/User Loops/.
AÌ? If you choose to index them at their current location, an alias to the folder will be
created in ~/Library/Audio/Apple Loops/User Loops/.