For example in JCE if you have wrote a new provider class you can
register it by called a method with a name something
registerNewJCEProvider ( JCEProviderInterface j );

I thought there might be an equivalent for your problem.

You can register new encodings with a scheme like this:
A charset provider identifies itself with a provider-configuration
file named java.nio.charset.spi.CharsetProvider in the resource
directory META-INF/services. The file should contain a list of
fully-qualified concrete charset-provider class names, one per line. A
line is terminated by any one of a line feed ('\n'), a carriage return
('\r'), or a carriage return followed immediately by a line feed.
Space and tab characters surrounding each name, as well as blank
lines, are ignored. The comment character is '#' ('\u0023'); on each
line all characters following the first comment character are ignored.
The file must be encoded in UTF-8.

Preferences has  a plug-in registration scheme that works like this:
If a PreferencesFactory implementation class file has been installed
in a jar file that is visible to the system class loader, and that jar
file contains a provider-configuration file named
java.util.prefs.PreferencesFactory in the resource directory
META-INF/services, then the first class name specified in that file is
taken.