Working visa for multiple entry for marine engineer from Croatia

Hi, I got job via one offshore company as engineer during conversion project from VLCC tanker to FPSO unit.I have to travel and work in Dalian with short brakes till end of 2015. My company have representative in Dalian and main office is in Brazil.Kindly asking you to guide myself in correct procedure to have required documents from my employer in order to apply for the type I need. Also.please let me know if necessary to approach with documents personally in Chinese embassy or by post mail. In my interest is to have it in fastest possible way. Looking forward to have proper instructions. Thanks in advance