Hi:
I'd recommend playing the songs with your guitar in standard (regular ol') tuning.
I don't know much about Chinese music, but there's no sense re-learning the guitar.
Chinese music IS based on a 5-tone scale, but so is lots of American/Western music (guitar-friendly). What's called the minor pentatonic ("5-note") scale is prevalent in the blues, etc.
When I introduce students to the scale, their first response is often that it "sounds Chinese".
The 6 open strings on the guitar comprise the notes found in the E minor pentatonic scale, so it could be said that the guitar is already "tuned to a five note scale", so the guitar may be well suited to imitate Chinese instruments, or at least to approximate the style.
In short: play the songs on your guitar as-is.
(But I guess the question remains: Does anyone know of a sensible open tuning that facilitaes Chinese-style guiter playing?)

Good Luck
-CC