Nice work Procyon. I've been using command.dat with Mame32FX .86 since I built my control panel some months ago and I gotta say that I love it. I even have a dedicated command.dat button that also presses pause on my CP. In fact, the only reason I use Mame32FX is because it has "native" support for the command.dat--and it seems to handle command lines very well, but I guess many versions of Mame32 can handle command lines pretty well. I'll check out the latest version of command.dat soon.
Cheers,
KenToad