will bribes work? 
Hah, depends what you're offering

In all seriousness this wouldn't be straightforward to add given how things work. That said, if you wanted to write a little program with your graphical menu for games list, you could potentially launch mamewah with /e and /l commandline switches to select the desired emulator and games list.
eg:
mamewah.exe /emame /l1
That would launch mamewah and select the 'mame' emulator and games list #1.
You could map a key to quit mamewah and return to your menu.