Hi. There are as many as 16 trains everyday from Shanghai to Zhengzhou, including three bullet trains which can take you there in 7 hours. Other trains may take over 10-15 hours. Suggest you go by train, more comfortable. Take express bus to Dengfeng (登封) at the long-distance bus center opposite Zhengzhou Railway Station (You can also found the direct bus to Shaolin Temple here). Get off the bus at Dengfeng Bus Station and take minibus outside the bus station to the temple.