In this paper, we present the PolyMAX module which enhances ns-2 (network simulator 2), the most popular network simulator used in academia, to provide one of the most complete simulation tools to evaluate the performance of Mobile WiMAX networks. PolyMAX is based on the NIST (National Institute of Standards and Technology) module and our specific contributions consist on the design and implementation of the QoS (Quality of Service) classes and QoS management messages, the uplink access grant-request mechanisms, adaptive modulation and coding, and a scheduler handling all five WiMAX QoS classes. We also present validation results for the different components of our module and typical WiMAX simulation scenarios illustrating its flexibility and some of its features. The PolyMAX module represents an important tool enabling researchers to easily implement their Mobile WiMAX scheduling and AMC (Adaptive Modulation and Coding) algorithms and accurately evaluate their performance for realistic scenarios.