how is initial xorg.conf generated? any options for this?

[Skunk Worx <skunkworx@xxxxxxxxxxx>]

i have a hard disk image i clone off with no xorg.conf under /etc/X11. 
it will be a live DVD soon--no way to know what chipset or display will 
be on the booting machine.

when booted into runlevel 3, and then "startx", i see an xorg.conf gets 
quietly generated on the fly.

Three questions:

1) Is there a way to set a default resolution in the generated xorg.conf 
file? Say 1024x768? would this even make sense not knowing the monitor type?

2) Is there a way to set "no dri"? some machines are locking up randomly 
on the first startx, they use the ATI radeon 7000 chip...commenting out 
load dri fixes this, but is there a way to (by default) not have dri in 
the initial xorg.conf creation?

3) If 1) or 2) are not possible, is there a place to hook into the X 
startup chain so i can run a script to make these mods?

Thanks,
SW