How challenging would it be to have the slider on the lock screen match the color of the battery power left from the visual battery seen on the lock screen? My battery turns blue when its full and then changes color when its near dead. To be able to sync the color of the slider to whatever the battery life is.
Depends how you want it.
You can hide the graphic files for the slider in winterboard and then remake your battery icons to lay below the slider. But it would be pretty buggy and only work when your iPod is charging