If you're interested in Interpretive Structural Modeling from a larger context than just John N. Warfield, you might also look down the branch developed by Aleco Christakis. Some of that shows up in Structured Dialogic Design, e.g. http://www.globalagoras.org/what-we-do/agora-reflections/sdd-process-review/ .
One route is through Peter H. Jones at http://www.redesignresearch.com/publications.html . I notice Jones, PH, Christakis, AN., and Flanagan, TR. (2007). Dialogic design for the intelligent enterprise: Collaborative strategy, process, and action. In Proceedings of INCOSE 2007, San Diego, June 25-29.