1. Is there a logo on the spacers? You could look them up and buy the key
2. you could see if the Crafstman brake cube would fit (or maybe modify it to fit) since it's cheap
3. you could go to a tire shop and show them the picture. They may carry the spacers or know/have the tool to remove them.
edit:
rolled up my sleeves and after ~ 5 minutes of searching:
http://www.shop.upgrademotoring.com/...?productId=378