Placing multicast proxies on the Internet can largely reduce the delivery delay of Internet live media streaming using overlay multicast mechanisms. In this paper, we propose a new approach to address the issue of proxy placement in an overlay multicast network. The task is to decide an optimal placement of multicast proxies in the overlay multicast network so as to minimize the average end-to-end delay of the overlay skeleton tree subject to out-degree balancing constraint and maximum delivery delay bound. We present two heuristic methods for this proxy placement problem. Experimental results demonstrate that proxy placement due to our proposed approach can greatly improve the overlay multicast routing performance. In comparison with an existing approach commonly used for replica placement in content distribution networks, our proposed approach significantly improves the end-to-end latency performance of overlay multicast networks, and is not much sensitive to network dynamics.