the icon to indicate a part is supsersed is very small. Only 9x9 pixels. superseded information is very important, since this indicates to your user that he should use other parts instead of the one he has found.
create a setting, or enlarge the icon by default, and make it more noticable. Use some Red colors in order to grow the awareness to the enduser something is going on.
If this is not feasable, create a way you can modify the icons in windchill , without actually overwriting the default icons. for example, create a custom location in the windchill directory which is empty by default where you can place your own icons, which are then picked up by wt.