Are you trying to do this in SimulationExpress? I don't think you can do it there, given the limits on the program.
Unless you are looking for some subtle interactions, you don't need to use Simulation at all to solve this problem. It's just a simple question of balancing the moments, done with a free body diagram. You just need SW to give you the center of gravity and mass of your part/assembly. Once the moment arm times the force is greater than the weight times the distance from the center of gravity to the pivot point, you're tipping.