From what I can find, MediaMonkey supports parts of the Winamp API, so it may support the same window messages.
I have a simple .exe that does nothing but send a "pause" message to Winamp(or any program supporting the same interface), attached to this post.
Run it while MediaMonkey is playing, and see if it has any effect(it won't display anything, at most you can see the process appear and quickly disappear in task manager).
The program is compiled with the VoiceAttack example plugin's "WinampLib" class embedded. I'm not sure what license it's under, but it's distributed with VoiceAttack, so I hope it's permissive enough for this type of distribution.
If the application works, you can use a VoiceAttack plugin to control MediaMonkey. The example plugin included with VoiceAttack can do this, but I don't think there's a compiled/documented version available at the moment. I can compile it for you if need be.