Answer
ArcGIS 8.x
Users are limited in controlling the symbology of raster catalogs. The rendering choice of the first raster in the raster catalog table determines how the entire catalog is rendered. The default renderer of the first raster, in the raster catalog, is the same as if it were a regular raster dataset.
For ArcGIS 9.x
ArcGIS 9.x has the capability to render heterogenous raster catalogs. This means that a raster catalog with different default renderers can be displayed with the most appropriate renderer. The raster catalog is rendered using default rules for each raster member- therefore users cannot pick the renderer for each raster member within the raster catalog.
Note:
Although heterogenous raster catalogs can be rendered, it is recommended that you make several homogenous raster catalogs instead.