umm... The docks is a place not too far from the Mad (direction west, a few hundred meters) where this night club often does alternative lifestyle/underground stuff and regularly has gay/lesbian night:
http://www.lesdocks.ch/
It's a cool place, relaxed atmosphere, I've had people hit on me there regularly.
The Mad also has some "bubble" evenings, I think it might be once a week on Sunday? Don't take my word for it as I've never been to it, just heard stories, but it's more of a "quick hookup" place:
http://www.mad.ch/
I've only been to the friday or saturday house/r&b/techno stuff there. Huge club, lotsa people. The bubble nights include placing foam all over the place and you kinda "grope" your way through it...
Don't worry about not speaking too much french, many speak english over here, and some quite well too. I'm sure if you go to one of the more gay friendly evenings at docks or mad, you'll be able to chat up other guys pretty easy.
Have fun.