Oh, I must be a bit confused then... I thought MAMEINFO was the name of the "extra" and then commands.dat worked in conjunction with it.
According to the commands.dat homepage, only Mame32 Plus and Mame32FX includes support for it, but if Mame32 Plus has a command-line version then it will work exactly like regular MAME, right?
Now if Mame32 Plus had support for that "press pause and see the controls" feature... (somebody here wrote it, I forgot the name of it and the person... sorry!)