Yes, Open the .wil from OldSkool and click export.
Make a new folder called items export on your desktop,
Folder = Select where you want to export them eg: Desktop/ItemsExport
it will say:
Image
Start {Select item where you want it to start the export}
End {The number of the item where you want it to end the export}
Example:
Folder = Desktop/ItemsExport
Image.
Start 1000
End 2500
This will export images from image 1000 to image 2500.
Once exported there will be a small file called placements that is exported aswell so you know how to place when you import them into your .wil
Then open your clients .wil and click import, then import into your .wil with the correct placements for each item.
You would have to do this for DNItems, Items and Stateitem.
This is how i did it anyway, maybe there is an easier way ?