This paper describes the integration of the High Level Architecture (HLA), an IEEE standard for distributed interactive simulation, with a scientific software package (Scilab) and its use for collaborative simulation development. This work is an on-going work that aims to facilitate the interoperability and reusability for Scilab simulation models. Integrating HLA with the engineering and scientific software package will enable users to apply simulation techniques to larger and more complex interactive and independent simulation models using networked computers, including virtual environments. As the HLA employs the technique of callback functions as a means for communication amongst the Run-time Infrastructure (RTI), the HLA middleware, and the simulation nodes, the integration was not simple. The paper also gives an example application showing how the HLA services are used to enable Scilab to construct distributed interactive simulations.