I have yet to find an example on the web (or in code) of anyone using the "Crop Coverage" Render Transformation from a Geoserver SLD. Does anyone have an example or at least be able to point me to the syntax of using an existing Geoserver hosted layer as a the "crop geometry?"

gs:CropCoverage is one of the WPS Processes used to crop raster layers.

This answer to Geoserver Raster layer cropped by polygon? provides an example of using gs:CropCoverage with a literal crop geometry, but I need to use an existing GeoServer layer as the crop geometry.

It is also possible to chain more WPS processes in a SLD but I cannot find an example of how to use gs:CropCoverage in a SLD.

At the moment I am using Geoserver 2.4.3 on Tomcat 6.