external user registration

[trhnapadu.cz]

Hi,
I work for one guy - he bought your forum and now, we want to
make big website farm, where all websites use one central
database. We want to make your database as the main, where
all users will be stored.

I know, what tables I must change during registration but when I
register someone in forum, some foreign characters are translated to
symbolic form. For example the letter from our alphabeth "č" is
translated to č And there is my problem - I can find function,
which can translate every letter, but I don't know, which letter your
forum translate and which not.

I can't find function in forum scripts for this translation.
Can you help me with that?