I was able to make play/pause, next, and previous buttons work using MCWS controls (e.g., MCWS/v1/Playback/PlayPause), and they work well to remotely control basic playback functions. But I cannot find a way to control navigation (up, down, left, right, enter, etc).
Again, this iPhone app is a universal remote that can control a whole theater or house through networked gateway devices such as the Global Cache GC-100-6 that will send IR or RS232 commands, through A/V equipment that have Ethernet connections through which they can be controlled, and through HTTP gateways (essentially, computers on the local network). You define an HTTP gateway with the IP address and port (e.g., 192.168.1.101:52199) and then send data to that gateway.
As noted, I'm looking for such commands to control basic keyboard and remote control finctions, such as left, right, up, down, enter, back, etc. Other programs have a whole host of such commands. For example, XBMC has an HTTP API with a plethora of commands that retrieve information, modify settings, generate actions, modify files, and the like. My needs are modest: I only want up, down, left, right, enter, and back buttons to control Media Center 15 in Theater View.