This paper presents the results of an effort to create a comprehensive and systematic procedure for developing warning message prioritization rules in integrated Collision Warning Systems (CWS) for heavy trucks. Although there are existing guidelines and even ISO standards for accomplishing this, in practice these sources are inadequate because they are not designed to handle the high degree of complexity and large number of warning conflict permutations that occur in integrated systems that have multiple subsystems, each with multiple warning levels. This paper presents a procedure that expands on existing sources, but has the level of detail and structured tools necessary to represent the variety of information that requires consideration when making decisions about the prioritization of warning messages.