Little Sheep Mongolian Hot Pot is where it's at. It's a Chinese chain. They do all you can eat hot pot. It's real tasty and a lot of fun. It's on the corner of Clark and La Gauchetière.
If you're looking for the western style fondue chinoise, I guess Fondumentale is fine, but I find that type of place kinda bland and the food not that great for the price.
Hiya, Fonduementale on St-Denis has Chinese fondue as one of its options - you might want to Google for some reviews (I saw a few good ones)...
4325 St-Denis St (near Marie-Anne)
If it's still there (this review is a bit old) La Fonderie at 964 Rachel East also offers Chinese fondue. See review here:
For something more truly Chinese, there's a great review of the Hot Pot ("real" Chinese fondue) at Yu Hang Restaurant - 400, boul. Rene-Levesque West - here:
http://www.montrealfood.com/ -scroll down about a third of the way
I've never been to any of these places myself, so I can't personally vouch for them, but since no one else has responded, I thought I'd give you somewhere to start your research. Let us know if you try any!