How to pass initdb LC_COLLATE & locale parameters when using wind ows? (with or without pginstaller)

Dear friends,

First pls accept my apologies, because I am a new Postgres user, so my
questions could be silly.

We need to setup a database using UTF-8 encoding, however, by some way, we
have to express our need for right Greek character collation order.
I tried the default installation using pginstaller, then I created a db
(using pgAdminIII) using UTF-8, but still the collation is wrong (=wrong
upper() and "order by") for Greek characters.

After some googling, I guess that I need to call initdb with the proper
locale.

Could you please help me with the below questions?
1. Is there a way to define locale options to the pginstaller?
2. If not, how can I (at least) create a new database with UTF-8 and el_GR
locale?

I am currently using Postgres 8.0 beta1 on Windows XP Pro, and having Greek
locale to my computer.

Thank you very much in advance, we really appreciate Postgres' superior
performance and features.

Greetings from Greece,
Tilemahos