I think your post is in the wrong forum. This forum is for the 2009 model WDTV Live HD and 2010 model WDTV Live Plus, neither of which support themes at all (except with third party firmware which isn’t really discussed much here.)
The forum for the 2011 WDTV Live Streaming Media Player is here:
http://community.wd.com/t5/WD-TV-Live-SMP-Discussions/bd-p/streaming_discussions
There’s numerous theme threads in that forum; all you need to do is search.
