[XeTeX] Hyphenation exceptions for German -- how?

[Thomas Fehige]

Hello everybody,

I'm trying to typeset a book with XeLaTeX. The main language is German, 
there will be other assorted Western languages like French, British 
English, Italian and Latin in small doses. I'm trying to enter 
hyphenation exeptions for German. The \hyphenation{...} command I used 
to use with pdfeLaTeX and the babel package seems not to work. What am I 
missing? Below is a minimal program that shows what I'm talking about. 
Oh yes, in case this is relevant: I'm using the TeX Live 2010 
distribution on a Windows computer.

Thank you for your time -- Thomas

%-----------------------------------------------------------------------
\documentclass[12pt]{article}
\usepackage{fontspec}
\usepackage{xltxtra}
\usepackage{polyglossia}
\setdefaultlanguage{german}

\hyphenation{
	einer
	Me-ta-ethik
}

\begin{document}
	\showhyphens{Metaethik, einer}
	% that gives me "Me-tae-thik" and "ei-ner",
	% the former wrong, the latter ugly.
\end{document}
%-----------------------------------------------------------------------