Can you do that without Winterboard? In each Apps file there is iTunesArtwork that is the default icon. I'm not sure if you can change that. With winterboard themes, they have folders marked icons or you can create them. You could create a theme using your own Wallpaper and add the type of icons you want. If you don't know how to create a Theme, you could just strip a lame Theme down and add what you want to it.
ok what if I wanna use the icon look from another winterbaord theme? the only reason I dont use the theme is because I cant use my wallpaper w it because of the 4.0 software or whatever
so just because I have different themes or whatever else in my winterboard doesnt mean they will drain battery life or cause the phone to slow down UNLESS they are checked and running correct? because I do have alot downloaded in there but most arent in use.