| Although I never participated (they're too early in the morning), the tai chi classes offered by the HK Tourist Office, or whatever they're called, are only for tourists.
That said, there is no guarantee that they would actually ask to check your passport or anything, but it may seem kind of suspicious if you were to show up to every class.
Then again, it might be a nice, one-time (and free) introduction to the art.
I imagine if you just do some searching around online, you'll find a plethora of tai chi teachers and schools in HK. How many of them that speak English... well, I guess that's another question.
L | 
I'd never make it back in time to get to work!
