Radeon G4 and Apple Cinema Display

[jerrell@inch.com (F. Jerrell Schivers)]

I'm trying to connect my PowerBook G4 (Radeon M9) to an external 20"
Apple Cinema Display, connected via the DVI port.  No matter what I do
I can't get anything to show up on the display.  All I want at this
point is to have the laptop's G4 screen mirrored to the Cinema
Display.

I understand that DRI doesn't work with Dual Head.  Will having it
enabled cause any harm?

Do I need to specify a ModeLine for 1680x1050 resolution?

Note: nothing comes up either from within a tty.  The Cinema Display
flashes white briefly shortly after a reboot, but then turns dark. 
Should I focus on trying to get that to work before worrying about X?

I'm using a recent rsync of 2.4.23-ben1.
The Cinema Display works fine under Mac OS X.

XF86Config-4: http://www.bordercore.com/public/XF86Config-4
X logs: http://www.bordercore.com/public/XFree86.0.log

$ COLUMNS=125 dpkg -l 'xserver-xfree86*' | grep '^[hi]'
ii  xserver-xfree86           4.2.1-14                  the XFree86 X
server
ii  xserver-xfree86-dri-trunk 2003.10.05-2              The XFree86 X
server [DRI trunk]

--Jerrell