The high Level Architecture (HLA) is an IEEE standard for interoperating simulation federates. In this paper, we describe a set of requirements that simulation packages need to satisfy in order to be made interoperable using the HLA standard. AutoSched AP, a commercial off-the-shelf simulation package (CSP) which is widely used in the semiconductor industry, was used as a case study for this interoperation exercise. We demonstrated that a straightforward customization of the CSP through a middleware that provides standard functions for interoperation may not provide a satisfactory solution. A specially optimized time synchronization mechanism needs to be installed to ensure good execution efficiency. Experimental results using a Borderless Fab model that comprises of two factory models show that an optimized time synchronization mechanism results in an execution time that is ten times better than a straightforward application of the HLA runtime infrastructure's time synchronization mechanism.