for the s2u2 you need to move the files into the correct folders and use the theme menu in settings. skinning the slider is a lil different, for that you need to move the .png files to the correct path as for a complete skin for all of 6.5 look under the themes and software thread in the tp2 forum. S2W has a couple real nice ones
Here is a thread on customizing s2u2:
[Guide] Customize S2U2 Battery Animation, Slider Button, Animation & Curtain - xda-developers