acad to gerber translation can be done by so called cam programs, to name a few:
#gerbtool
#camtastic
#cam350
#camcad-pro
I have seen free licenses and so called "cracks" for all of the above.
plot from acad to hpgl (7475,7580) and search for
converter hpgl->gerber . This is easy way, but -
maybe acad will draw with very thiny pen and file will be too long -> on non-laser gerber ploter this will be too slow and maybe - not good enough.
I have a program I never used ( I use Camtastic) called Autogerb3 that I believe was a free download from Protel at one time. It is supposed to work with Acad R14 & 2000. I'll e-mail it to you but I need your address.
Steve Smith
Product Engineer
Staco Energy Products Co.