If you're reading this, you aren't using WinRAR, so WHY THE FUCK ARE YOU NOT

Place ITG 3 - Encore in your Themes folder (I have no idea
where to put it if it's for your Dedicab or OpenITG AC cabinet)
Place NoteSkins in the root of OpenITG. Say yes to overwriting
the files, it'll still work.

Enjoy your widescreen ITG 3 Encore theme~