Thanks for the replies, everybody.
I have heard first-hand stories of equipment being seized by customs from several people at companies that we work closely with (one story from the company that contracted us to do this job). I am in contact with a post production studio in Shanghai, who is helping us to try to locate Pro Tools rentals in the area. They mentioned that they have had clients that have had problems with Macs being seized by customs. I have no doubt that many people have had no problems with Chinese customs, but due to the large value of equipment that I need for the job, I don't really want to risk my own gear.
I received a suggestion to contact the Chinese Digidesign dealers listed on the Digidesign website, which I will do today, but they are all in Beijing, so I may have limited results.
Thanks for the suggestion Big Andy, I will add Technicolor to my list of leads.
Thanks again for all the help everybody.
This forum is an amazing resource!