I'm not familiar with Mamehooker,  but the first thing I'd try is to launch a second instance of Mamehooker.  This might require doing a second installation,  to a second directory.  Some programs you can do that with,  some programs you can't.
I've actually toyed around with the idea of writing a app/plugin that would display the control panel/instructions(For consoles) and even a list of special moves to a third monitor,  but interest seems pretty low in it so I haven't pursued it (Especially since it involes me buying a second monitor).
The other idea I've toyed with is a touchpad and a wi-fi built in,  setup an app on the computer and the touchpad,  and then broadcast the game to the touchpad which would then display the above.  Might actually be a cleaner solution,  since 3rd monitors in this configuration tend to be those RGB or USB models which introduce problems.