David,
Try this link:
[CentOS] Remote-logging nginx? (or other non-syslog-enabled stuff) - Grokbase
If you scroll down a bit llyas shares a solution. I hope that gets you going in the right direction.
How do you like nginx? I've yet to spec a web project so I have to support what's already there or what gets spec'd and it's usually Apache and occasionally IIS. Curiosity gets me looking at nginx from time to time though, and I've installed it on a test box or three in the past.
Acy