You only need the "TW Covers" if you want different covers for your coverart thumbnails. Those templates are different than the No Cover box template and look like THIS.
There's really nothing to installing the theme. All you have to do is unzip the entire "Mojo 1.10.02 (MS)" folder to your PC (make sure you unzip it to your PC first, not directly to the HUB). Then from you PC, go to the HUB which you should have already mapped the drive. Open the folder "wd_tv", if you don't see it and your running Windows 7, click on "Organize" at the top of the Explore window, then click on "Folder and search optons". In the new widow, click on the "View" tab and under "Advanced settings" check the bubble next to "Show hidden files, folders and drives".
You should now see the "wd_tv" folder. Open it and you should see a "theme" folder. Open it and this is were you will copy any themes you want.
If for some reason you don't see the "wd_tv" folder, you can just created a new folder and name it "wd_tv", then open it and create the "theme" folder.