How to add new SRS/Projection/WKT to the GDAL database

I'm using GeoServer, OpenLayers(3.0) and the GDAL utilities.

GeoServer has one (or more) SRS/Projections that is/are NOT present in the GDAL database of SRS/Projections.

I can get the well-known text (WKT) for SRS/Projections from Geoserver. For example, EPSG:404000:

LOCAL_CS[“Wildcard 2D cartesian plane in metric unit”, LOCAL_DATUM["Unknown", 0], UNIT["m", 1.0], AXIS["x", EAST], AXIS["y", NORTH], AUTHORITY["EPSG","404000"]]

...the GDAL database of SRS/Projections consists of a bewildering number of csv, prj, and wkt files that installs to %GDAL_INSTALL_HOME%\bin\gdal_data

(apologies for windows-centric path conventions)

...is adding EPSG:404000 just a matter of editing one (or more) of the csvs? If so, which ones? If GDAL.org has documented the procedure, I'm having trouble finding it. Can anyone shed light on this?

Thanks

Jim Pollard