Sanibonani,

I am listing some of the schools that I know/have heard about that offer Zulu classes.

We have classes here at IU. See the site: http://www.iub.edu/~afrilang/

Also try University of Wisconsin, Illinois (Urbana-Champaigne) and
Yale- http://www.yale.edu/macmillan/african/languages/sanneh.htm

I think they also have classes at other universities in US and then there is always the summer intensive program. Here are from previous sessions:
http://scali.afrst.uiuc.edu/
http://www.indiana.edu/~afrist/scali/

That should get you started.
Madeleine