Well . I've not tried Kawaks with Mamewah. I have got Nebula to work to a point .. I can get the games list up, get the loading 'Nebula' screen up at full size, then it kinda 'flashes' and goes back to the games list again. I have noticed that when running Nebula from Windows, it works fine, but a whole bunch of loading blurb appears on the left hand side of the screen in a progressive list .. which would be better off hidden.
Thanks for the input, it's saved me going the Kawaks route .. but I'll google to see if anyones managed it too.