SQL & PL/SQL

I am finally making my first leap into regular expressions. I've read the good tutorials posted here and other places but am struggling with how to convert extended characters into their base letter equivalents.

The requirement is to process a string as follows:

1. Convert to uppercase

2. Convert extended characters to base letter equivalents using this mapping:

ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÑÒÓÔÕÖÙÚÛÜÝ
AAAAAAACEEEEIIIINOOOOOUUUUY

3. Remove any characters other than A-Z, 0-9, and space.

So, the string:

10. Chëur «Die Katze lässt das Mausen nicht»

would be converted to:

10 CHEUR DIE KATZE LASST DAS MAUSEN NICHT

with t as (select '10. Chëur «Die Katze lässt das Mausen nicht»' string from dual)
  select string, regexp_replace(string, ???, ???)
   from t;

Thanks for any help on this.

-Todd