Homebrew PCBs

I'm new to the group, but not to making PC boards.   I'd like to try
milling a few prototype boards.  I have a CNC milling machine.  I use
Linux tools, xcircuit and pcb.  

How do I convert the gerber files to G Code ?  Does anyone have source
for a utility to do this ?


-- 
Kim Lux (Mr.)  Diesel Research Inc