You could put the cellfile in a pmap file and output it to the ppm driver
in GRASS which creates a paint.ppm file in your home directory that you
can then use with the pbmtools.
We haven't had much luck using the cell driver and the rawtoppm ourselves.
Let us know if you are successful going that route.
Brandy Riche
lewis!brandy@cerl.cecer.army.mil