I'm going to assume for whatever reason, using miles isn't possible.

Resign yourself to the fact that if you want this all on one PNR, you are not going to be able to do it by yourself online and get it to come out right. If you can find a Chinese-reading friend, you can try getting them to help you navigate the Chinese version of the website. Failing that, either go to or call (good luck!) the office of MU or CZ and get staff to help put this together. Or go to a travel agent and have them sort it out. Remember that if you want to earn miles, the heavily discounted booking classes may not earn you anything for Delta Skymiles--you will need to tell whatever agent helps you that you have minimum booking class requirements; otherwise they will set you up on price alone. So decide what's more important in advance: price or earning miles.

If you are willing to deal with more than one PNR, you might have a shot at doing it yourself online. In which case it would be logical to have the international SIN-China-SIN part booked separate from the intra-China legs. And you may need to use separate airlines and separate booking sites to optimize pricing. You can also try open-jaws SIN-NNG and LIJ-SIN and see if that helps you out...however, my suspicion is that online efforts will produce some weird connections and lousy timing and not necessarily have all possible options. Or try a straight SIN-KMG-SIN. Chinese segments can be done on ctrip, elong, travelzen but you'll probably need to book segment by segment.

If you go the travel agent route, this is likely going to be best done with a Singapore-based travel agent. One you might try (can also play around with their online functions yourself before calling for assistance) is MISA: www.airfares.com.sg.