Buy raw land in the near suburbs of Beijing, Shanghai, or a slightly smaller but growing city. Choose property that is slated for light-rail and other major infrastructure development. Hold it until most of the surrounding parcels are developed and then sell to the highest bidder--probably a major Chinese developer, the Chinese government, or a U.S. multinational.
Open a school for entrepreneurs. China is said to be a country of a billion entrepreneur but because China is new at this capitalism thing, many of those entrepreneurs have a lot to learn. And they're smart enough to realize they can learn from Americans, a people that has been entrepreneuring for 250 years.
Sell designer-label products (e.g., Calvin Klein) to the major retailers in 50,000-100,000-person cities. The big U.S. corporations are still busy establishing their distribution chains in larger cities. The opportunity for a little guy is to go where the big.U.S. corps aren't (yet.)
Sell precision manufacturing parts and equipment to small Chinese manufacturers.
The satisfactory execution of such ideas require one or more trips to China or taking residence there. It requires getting a translator and, critically, local expertise. Start with the U.S. Chamber of Commerce there, but that's just a starting place--you'll have to take the time to build local relationships.
The bad news is that Woetzel said that China is very China-centric. So Americans have one or two strikes against them. And the Chinese have a set of business tactics designed to weaken Americans--for example, they'll stall on agreeing to a deal until just before your return flight to the U.S, when you're most vulnerable to a lowball offer.
But if you diligently and intelligently execute on the above, people like Woetzel, the N.Y. Times' Tom Friedman, and a chorus of other folks, including me believe that China and smaller emerging Asian countries offer a far more fertile opportunity for success and wealth than does the U.S.