How do I set the inital pose of a robot in gazebo?

Let's say I've created my own world file that has: This normally spawns the robot at x=0, y=0. How could I spawn it somewhere else, say x=1, y=1? I know I could spawn the robot and then move it by calling the service: set_model_state, but I've found doing this with the pr2 doesn't work very well with other objects in the world. pr2_no_controllers has an arg called 'optenv ROBOT_INITIAL_POSE.' How do I get at this from my world file?