Not sure if this will help, but in a dos box attrib -r /s *.* marks everything as writable below the current path. I did this on my install the other day when settings were not being saved and it worked fine (if you have a lot of roms it will take a while). Someone else can probably help with exactly what files need to be writable, but I just went ahead and made everything writable, they were only ever read only because they were copied off a CD.