I found that the cause of this problem is that, when using the custom xorg.conf (and presumably failsafes?), the vesa module isn't loaded. Simply adding a Modules section to the custom xorg.conf solved the issue:
Section "Module"
Load "vesa"
EndSection
This combined with the custom monitor settings finally allows Lucid to display 1024x768 across the full LCD, which allows the woraround for bug #288807 to function again.
I found that the cause of this problem is that, when using the custom xorg.conf (and presumably failsafes?), the vesa module isn't loaded. Simply adding a Modules section to the custom xorg.conf solved the issue:
Section "Module"
Load "vesa"
EndSection
This combined with the custom monitor settings finally allows Lucid to display 1024x768 across the full LCD, which allows the woraround for bug #288807 to function again.