force grayscale

[Toni Casueps]

The Linux driver for my printer does not allow choosing between color or 
grayscale, so I can only choose if the program options allow it. I want to 
make a filter in kdeprint so that every program that prints through it can 
print in grayscale, I found the ghostscript command that reads a color PS 
file and outputs a grayscale PS file but I don't know how to insert it into 
my kdeprint options. Can you help me?