Try adding these options to the device section. If it doesn't work, try swapping the two resolutions around in the 'MetaModes' Option. I haven't found a way of telling the driver which device to find first (in fact that's why I'm here!).
Option "TwinViewOrientation "Clone"
Option "SecondMonitorHorizSync" "30-50"
Option "SecondMonitorVertRefresh" "60"
Option "MetaModes" "1024x768,800x600"
..and these ones I can't tell you the values to use...
The first will be probably be "DFP,TV" for a laptop panel (but it might not...). TVStandard depends on where you live ("NTSC-M" for the US). TVOutFormat is either "COMPOSITE" or "SVIDEO". Composite is the phono plug, which is probably what you've got. S-Video is the annoying little one with lots of pins that nobody uses.
That should get you started - all the optionsd are explained in detail in the README file.