A character set defines the basic alphabet supported by a database. An encoding then maps the character set to the 1s and 0s understood by a computer. MySQL comes with support for a variety of character sets and encodings. Unfortunately, this support is very peculiar. MySQL ties the concepts of character set, encoding, and sorting rules together so that these three normally distinct concepts cannot be separated. While this scheme works well if you use one of the supported character sets with the built-in sorting rules, you may need to go to some extra lengths if the character sets that come with MySQL do not meet your needs.
First, you need to determine whether the character set needs special string collating routines for sorting and whether it needs multi-byte character support. If it needs either of these, it will need to be compiled in. Otherwise, support for the character set can be added by simply modifying the configuration.