Did they even know about the Chinese? I have my doubts that the Polynesians who visited South America OTL ever even heard of China, the Philippines, or any other country which China traded with. Goods from South America would pass through many hands.
Easiest root is to have the Galapagos settled by the Polynesians (from Rapa Nui), who then cross back around to the Marquesas, then the Line Islands, then Hawaii. The Hawaiians trade with the Micronesians (Marshal Islanders, Chamorro, etc.), and settle the Bonin Islands, and from there trade with Japan, who will then trade with China. This will not be a maritime equivalent of the Silk Road, the volume of trade will be pretty low. Disease will take centuries to jump from island chain to island chain (but having each new disease "staggered" is pretty nice compared to OTL). Almost no one will make the voyage from the Andes to Japan or China for the first few centuries, not until some Zheng He equivalent (who will be using ship designs the Chinese OTL never used, as the Pacific Ocean is not a pacific ocean) comes along and decides to visit these islands. Anything past the first few island chains will fade into myth and legend (like believing Nan Madol is in South America or something). This means almost no one will know the ultimate source is South America, since they'll just say they got it from the guys on the next island over.
When the Zheng He equivalent arrives in Chan Chan or wherever, then we'll see some Chinese communities emerge in the coastal towns (and some major inland cities), and a corresponding increase in the amount of trade flowing across the Pacific.
For the sake of this thread, the Polynesians need to be expanding across the Pacific a lot earlier than OTL to get this whole thing set up before the Europeans show up. Unfortunately, the death rates will still be pretty high, but (mostly) peaceful Chinese merchants spreading disease is a better scenario for the natives than conquering religious fanatics. And even if the Polynesians are settling earlier, the fact this trade route will take so long to emerge means there's likely to be precious little time left before the Europeans show up.