You must be in the Security Administrator role in the global zone. You must have an encodings file that does not have a LOCAL DEFINITIONS section.
Add the LOCAL DEFINITIONS section to your file.
Append the section from a Trusted Extensions-supplied label_encodings file. Trusted Extensions-supplied files are in the /etc/security/tsol directory.
Customize the extensions for your site.
For details, see Modifying Sun Extensions (Task Map).