There's no plug-and-play option. You could probably create yr own custom wall type that analyzes similarly to the strong-wall. Basically try to get the capacity you need, and then have the program distribute the forces based on capacity. Either way, I would be double-checking the results and maybe doing it one or two ways to check.
If flexible diaphragm is all you plan on doing, specify a shearwall where you intend to put your strong wall and grab the load from the model to design your strong wall by hand. If you are also doing rigid diaphragm design there is an option to specify the relative rigidity of your walls in the settings design tab. If you know the stiffness of the light-frame walls and strongwalls, you can assign a relative rigidity to all the walls in the wall input based on the wall with the lowest stiffness. This sort of question would be answered by their tech support.
