There are three three-hour group courses coming up at the Migros School (taught in French):
http://www.ecole-club.ch
Type "inline" in the search box to find these results:
Stade de coubertin, 1000 Lausanne Sa 02.05.2009 09:00-12:00
Stade de coubertin, 1000 Lausanne Sa 16.05.2009 09:00-12:00
Stade de coubertin, 1000 Lausanne Sa 20.06.2009 13:30-16:30
Price is CHF 63.
You'd have to visit the school in the Flon to sign up.
BTW, I'm in no way connected to the Migro School and have no idea whether the courses are any good, I just remembered seeing them listed in the brochure.