Well, after having this set up, I wanted to be able switch resolutions (the screen is really tiny, and it drops the frame-rate of games rather significantly) I tried all of the standard xorg.conf configuration, addmode, newmode, all of that. But nothing worked.
Today, I stumbled on a solution: xrandr's --scale option. This allows you to scale that screen to almost any resolution you want.
(this returns certain names e.g. mine is DP-2. Another is HDMI-0. One will say "connected" and that's the one you need.
- xrandr --output DP-2 --scale .5x.5
This scales it to a 1440x900 resolution.
One thing to note. Sometimes trying to go from one scaled resolution to another will fail with an error. Don't panic: just change the scale back to 1x1, and the next scale you choose will work. The scaling numbers don't have to be simple: I managed to get ~1650x1050 by putting the scale value as .5729x.5729.
Here's a link to the script: https://gist.github.com/4552263/
This script takes one parameter: the width in pixels of your screen.
sh ./Res.sh 1680
The result is a 1680x1050 scaled screen.