Hi Jay-
It always goes back to basics. What would you do first with any other group of students? Assessment, of course. The first class can be a brief assessment/analysis of their general problem areas (Chinese speakers have specific problem areas that you are probably already aware of--you'll probably focus on those) and also ask them what the problem areas are that they want to focus on.

In the past I've used "tongue twisters" or simple sentences that are heavy on a particular sound (th, r, s, sh, l, t) being repeated through out the sentence. Remember to put that sound at the beginning of words, in the middle of words, and at the end of words. (I don't have my little booklet of my favorites with me right now, but I'll come back in a couple of days and give you examples.) I introduce a new sentence in each class and practice it for 20-30 minutes, and give it near the beginning of the class, and try to remember to include that particular sound or letter often during the class.

Let them know on day one that they will be responsible for much of the practice they get during the course, and that if they don't participate they won't improve (the onus is on them to improve, not upon you.) Encouragement, encouragement, encouragement. Maximize their talk time, minimize yours. You can use activities such as debate and negotiation, and give an assignment of them to give a presentation in the class. Part of that assignment will be to include the two or three most difficult pronunciation problems they personally have and to include those sounds in their presentation at least 5 or 10 times.

Good luck. If you view this as a learning experience for you and do well with it, it looks good on your resume. "Duties included teacher trainer."