how to add additional languages

hi everybody

i am trying to add additional language for client web interface like "request type" /  "subject" and etc..

i know that i should make a copy of the "Labels.properties" file and rename it to for example "CustomLabels_XX.properties".

but my problem is how to use native2ascii for encoding?

the syntax is :

native2ascii -encoding "<encoding_name>" [input_file] [output_file]</encoding_name>

but can anyone help me about the exact way of using this encoding???