The CSS textures and models are somewhere in the second folder of the /pf/system/common5.pac file. Just open it with brawlbox, and do whatever changes you need to.
Yeah, I am familiar with where it is; although it's not in a common5.pac, it's in a seperate file. What I tried to do is turn the CSS Icon name into a transparent image, but a white strip takes its place. So I'm probably doing something wrong.