perhaps you have downloaded the extension contents but the images are located in the default base design that comes with eZ. Do you have access to the full eZ folder installation? Perhaps would be more easy to find things like this if you see the entire eZ struct....
hope this helps!
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Xavier Serna
eZ Publish Certified Developer
Departament de Software
Microblau S.L. - http://www.microblau.net
+34 937 466 205