IIRC the

1~/dosbox.conf

file does not exist on a Mac for DOSBox 0.73 and the contents are found instead in

1~/library/preferences/DOSBox 0.73 Preferences

and this file is automatically made when you first start DOSBox.

If I do recall correctly, perhaps this would be a good thing to add to http://www.dosbox.com/wiki/Dosbox.conf#Technical_aspects, as I couldn't find it on the Wiki at all.

thanks,
Oscar