I'll definitely add my agreement about getting car service. To find one, just do a search and you'll see all kinds of posts about them.

As for your Chinatown destination, there is a chance that your driver may not know exactly where your destination is so you might want to get the nearest major cross-street to give as a reference point for your driver. Since you could be cutting it close, I'd hate to see you waste time by trying to find a very short street.