After my collegue Tom did the first trick, I finally managed to get WP-ML up and running on NGINX (updating to wordpress 3.0-release did miracles). I already made a change in the “Resume/CV” part which is now bi-langual. You will not see it in the regular blog, but if you click the appropriate language on the right handside, you will get only posts within that language.
It makes it a bit more difficult this way since it used to be all in one post, but well, you will manage ;-).
I will take some time to slowly convert all posts from the Polyglot setup to WPML. Tom had created a nice little script for that, which I need to tweak a little (his native language is NL, while mine is set to EN, should be a trivial change, but nevertheless I will proceed with caution :)).