If you want to theme Swype, decompile the apk with apktool. The keyboard images are in the assets folder.
Now here is the good part, I'm pretty sure it is legally stated that since Swype comes with our phone we are entitled to new versions of Swype on our phone and included in third-party ROM's. That means you can download the beta Swype 3.x, decompile the apk, theme it, recompile it, crack the licensing, sign it, and then use it on your phone or ROM.
Before I get in trouble for saying it though, it would probably be better to check with a moderator. Keep that in mind!
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