It turns out it is possible to use QTX with Perian:
http://foolrulez.org/blog/2009/09/snow-leopard-playing-mkv-with-perian-and-quicktime-10/
Maury
http://foolrulez.org/blog/2009/09/snow-leopard-playing-mkv-with-perian-and-quicktime-10/
Maury