If I am not mistaken, the important part of CC licenses is that they are not necessarily viral.
For example, CC-by (aka CC-Attribution license) allows the authors of derivative works to change the license terms, as I understand. If you modify the work, you should still make an attribution. But you do not have to license that derivative work you created under the same (CC-By) license. You can fully copyright it, or you can release it under GFDL.
CC-by-sa (CC-Attribution-Share Alike) is a different story. That is viral and requires derivative works to be released under the same licenese. This, I think is clear when one compares two license terms, especially the part 4-b. And here are the links:
http://creativecommons.org/licenses/by/1.0/legalcode
http://creativecommons.org/licenses/by-sa/1.0/legalcode
Sorry if I am mistaken. But if I'm right, you can create some derivative work first, and you can release it under GFDL. I hope someone else can double check the legal code on this point.
regards,
Tomos
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