Adding new EPSG codes to Geoserver

I am posting this here in case anyone knows the answer!

I am trying to get Geoserver running to server data from a PostGIS
database to both WFS and WMS. I've had this running in the past, in
versions where Geoserver didn't care about the projection you were
using. However, I have hit a snag, as follows.

I have updated to Geoserver version 1.3RC2, and it has a lot of good
thigs including good support for JPEG. However, when I attempt to load
my data, I can't because Geoserver does not recognize EPSG code 3031
(which is widely used in Antarctica).

I had a poke around and found the epsg.properties file tucked away in
gt2-epsg.jar, which contains a list of WKT definitions for epsg codes.
I modified this to include a definition for EPSG:3031, remade the jar
and find that the capabilities document from the WMS shows EPSG:3031
as being available. So far so good.

Unfortunately, when attempting to link to data, it does NOT recognize
my definition of epsg:3031! I get an error like:

Could not find an SRS Authority that understands your SRS. Please
verify that your SRS is correct - you might need to consult the SRS
authority plug ins to ensure that your SRS is listed.
Unabled to locate code
EPSG:3031

Is there some other place that Geoserver is keeping a list of EPSG
codes? It really ought to be user modifiable, as the EPSG code list is
constantly changing - I just submitted around 90 new definitions a
month or so ago!

Thanks

Paul