Hi, I haven't tried this, but I guess it should work.
Your 'display' in attract.cfg has an romlist name. This romlist name needs to match the romlist file in your attract/romlists folder.
Always make backup before you edit any files.
Open the romlist you want to edit in a spreadsheet editor, select 'Semicolon Separator' as file type method. When finished just save back over the original txt file.
Emulator column is name to match the emulator cfg file in the attract/emulators folder. So, basically mame games will have mame here and you can put what you want for 'other stuff'.
Go to attract/emulators folder and you should have a mame.cfg for settings to run mame games. Now, you need to make ___.cfg for the 'other stuff' that you setup in in the romlist file in the spreadsheet program step above. The file name needs to be an exact match. Fill out the run command settings, artwork paths ,etc..
I think that is all you would need to do.