FTS lucene and english + german mails

Hi,

I'm currently looking over the FTS pages to enable it in my dovecot. But I'm unsure what the best settings of the lucene plugin are, if you receive german and english mails. Wiki says:

textcat_conf=<path> textcat_dir=<path>: If specified, enable guessing the stemming language for emails and search keywords. This is a little bit problematic in practice, since indexing and searching languages may differ and may not find even exact words because they stem differently.

On Debian libstemmer is included in the debian-lucene package.

So what settings are the best to have not the problem that exact words can't be found?