Install: Japanese support: what options to give to ./configure?

Hi, I'm new to PostgreSQL. I just download the source and want to begin
compiling it. However I am not sure what options to give ./configure.
All of the data for the database will be in Japanese or ASCII.

I want to configure the data so that it can store japanese without
mangling and can also sort, and execute LIKE on japanese data properly.

Which options should I enable?

Here are some questions I have:

--enable-locale

I am confused as to wether I need --enable-locale or not. And if I do
need it my I don't want ./configure to use my environment vars to figure
which locale to use since the machine (Linux) is setup for english (C)
and not japanese.

--enable-multibyte=EUC-JP

Why is this necessary? What is the difference between this and
--enable-locale, or between ./initdb -E EUC_JP

./initdb -E EUC_JP

Is this necessary if I use --enable-multibyte=EUC_JP

In short do I need all three of these settings or just one or two?